Roofing with PVC sheet

• The applications of corrugated PVC sheets
• Types and sizes
• Buying PVC sheet
• Hints on working with PVC sheet
• Weatherproofing
• Sealing with adhesive flashing
• How to fix the sheeting to the roof framework

Transparent or translucent PVC sheets, corrugated to add strength and rigidity, can be used both for roofing and for cladding walls. The material is lightweight, so it is easy to handle. And it is simple to cut, making it ideal for DIY work. Among the applications to which it is admirably suited are carports, sheds, lean-tos and conservatories. If you need roofers in London, contact us.

And, although this feature concentrates on using PVC sheeting for roofing, most of the details apply to wall cladding as well. Types and sizes The most popular type of sheeting— ’75mm round profile’ has smoothly rounded corrugations with a distance from one ‘peak’ to another of just under 75mm. Sheeting with squaredoff corrugations is also available and again, the distance from the start of one corrugation to the start of the next is about 75mm: this is known as ’75mm box profile’. Some sheets have smaller, rounded corrugations and are known variously as ‘mini profile’, 38mm, or 32mm profile.

These are best suited for wall cladding, or for short roofing spans such as those found on lean-tos. A larger, heavy duty sheet is available for particularly big roofing jobs. The 75mm profile type usually comes in 760mm wide sheets, measured across the corrugations. Lengths vary from around 1.5m to 3m. Modern transparent sheeting is very clear and lets through most of the available light, but you can also buy translucent clear and coloured sheets including a semi-transparent white.

Buying PVC sheet

Some brands of sheeting, although clear when they start life, become opaque over the years with the action of sun and rain. If it is particularly important that the sheet remains clear for example, if you want to use it in a conservatory or greenhouse, make sure you pick a brand that guarantees clarity. Even clear sheeting varies in its ability to let through light so again, if you are planning a greenhouse, pick a brand that lets through the maximum amount.

When you are selecting sheets, check that they are not split, damaged, discoloured, or distorted. When you get them home, stack them flat—on battens and covered with a tarpaulin, if they are left outside. Although you should never stack it in direct sunlight, cold weather makes PVC brittle and it is a good idea to leave the sheets in a warm room for a day before cutting.

When you are calculating quantities assume each sheet covers about 10 percent less than its actual area to allow for the overlap at the sides with adjoining sheets. At the same time, buy a supply of purpose-made fixing screws, allowing roughly 25 for each square metre of roof area. Round-head chrome plated screws, 45mm long, are the best for roofing work. Special plastic caps and washers are needed to waterproof the holes through which they go, so it is sensible to buy a supply of the fixing accessory packs that are sold for use with the sheeting; indeed, if you do not, you may lose the benefit of any guarantee you get.

The structure which supports the sheet is normally timber and often ends up more complicated and costly than the covering itself. Choose only well-seasoned timber and make sure that it is adequately preserved before you fit it. Bear in mind that you may need flashing materials to seal a joint between the sheet and an existing wall. Working with PVC sheet PVC sheeting is quite easy to cut and drill, providing you follow some simple rules.

It can be marked for both with a felt-tip pen and obtrusive marks may be removed by rubbing with a cloth soaked in methylated spirit. One handy hint which aids marking out is to cut a strip of the material and use this as a template for all further cutting. Cutting is best done with a tenon saw or fine-toothed panel saw, though for cutting off small pieces you could try tinsnips or a pair of heavy scissors.

Cut at a shallow angle, and support the sheet carefully on both sides of the line down which you are cutting . In cold weather it is best to cut indoors—and handle the sheeting especially carefully. Holes for the fixing screws should be drilled slightly larger than the diameter of the screw shank to allow the sheet to expand freely. With the type of screws usually used for roofing, a 7mm hole—giving a clearance of about 3mm—is ideal.

Support the sheet on the opposite side to which you are drilling the hole and do not allow it to bow under pressure. Both hand and power operated drills can be used, together with ordinary twist bits, but you may find that a slightly blunt bit makes a cleaner hole than a new one. Make larger diameter holes by drilling a circle of tiny holes—say 3mm diameter and then joining these up with a fine padsaw blade. In this case increase the clearance for expansion to around 4-5mm.

The corrugations on PVC sheet give it some degree of rigidity, but it still needs to be well supported if it is not to fly off in the first high wind. The main supports are purlins—the timbers which run at right-angles to the direction of the corrugations in the sheet. These should be set no more than 600mm apart—so a sheet 1.8m long must be supported top and bottom and by two inbetween. The purlins, which generally measure 25mm or 38mm in width, are in turn supported by rafters running at right-angles to them along the direction of the corrugates.

The distance between the rafters depends on the depth of the purlins.If your roof is small and you use thick purlins – you don’t need rafters, the purlins can be supported on whatever forms the ends of the roof structure.

Weatherproofing The easiest way of ensuring that a simple structure is reasonably weathertight is to allow the sheets to overhang it all the way round. The amount of overhang at the bottom of the slope depends on whether you want guttering: if you do, arrange the overhang so that rainwater will flow properly in to the gutter; i f not, have a larger overhang so that the rain is thrown clear of the base. An overhang of 250mm would not be too large. For a more airtight structure, the top and bottom can be filled with eaves filler strip, foam strip in the shape of the corrugations. The strips should be placed on the supporting timbers before the sheets are fixed in place and the fixing screws driven through them. Hold the strip in place as you insert the screws.

Overhanging sheet looks unattractive if left by itself so for a neater appearance, fix fascia boards all round—whether you are fitting guttering or not. The fascias are best fixed directly to the purlins or rafters, so arrange for these to overhang the structure by a suitable amount. Whatever the size of your roof design, you should make sure there is a slight fall towards the gutter edge and along the corrugations, not across them.

A fall of 10° or more is preferable although much steeper slopes can be used if you want. Try to co-ordinate your design and the sheet sizes so that you do not have to join sheets end to end. Alternatively, redesign the structure to suit—for example by turning the slope through 90°, or siting the gutter in the middle of the span, rather than along one edge. If you do have to join sheets end to end, they must be overlapped by at least 150mm with a purlin below.

Flashing

There are two main methods of sealing the joint between the sheet and a house wall. The easiest is to use proprietary, flexible, self-adhesive flashing strip in conjunction with its own bituminous surface primer. This is easy to apply, and is pliable enough to fold into the corrugations. An alternative method where the corrugations are to run at right-angles to the wall. Here, you lay the sheets half way up the final purlin—which should be wider than the rest—then fill out the rest of it with strips of packing timber, the height of the corrugations.

You then lay a final timber strip the same width as the purlin over the sheet ends and the packing. Push this up against the house wall and secure it by nailing through the packing to the purlin. Seal the gap between the wall and the strip by packing i t with a suitable mastic. The same technique can be used to form a pitched roof ridge’. Where the corrugations run parallel to the house wall, a wall plate carries the ends of purlins rather than rafters, and the fixing and sealing arrangements are a little different.

Round profile sheet can be sealed to the wall plate with bevelled timber packing pieces—one above the sheet, and the other below. Bed in the edge of the sheet with mastic. The technique can be used with box profile sheet too, but a neater method is to cut a groove in the wall plate with a circular saw, and to ‘spring’ the edge of the sheet into this. Remember to cut the groove at the same angle as the roof slope and again, bed in the sheet ends with mastic.

Double glazing

Heat loss through PVC sheet is very high, and this makes i t unsuitable for use as a permanent room. However, some of the heat loss can be reduced by ‘double glazing’—fixing another layer of sheeting to the underside of the supporting purlins. In this case, weatherproofing is unnecessary and you can fix the sheet in its valleys, using shorter screws.

However, it is important to seal both exterior and interior layers, so that the air in the cavity is still. Use eaves filler strip at the edges, and overlap joints in the same way as for the exterior layer. If there are rafters in the construction, cut the sheet to fit between them and seal the joints between the two. It is essential that both interior and exterior layers are of the clearest sheet you can get—less transparent sheets may lead to a build up of heat in the cavity, causing them to warp.

Fixing the sheet

When you come to fix the sheets to the supporting structure, you may find yourself doing more than one job at once. For example, it would be better to fit self-adhesive flashing as you go along rather than leave it to the end and risk falling through the roof. And, if you are sealing joints, have the necessary materials to hand before you start overlapping. On a roof, the idea is to have the joint overlaps running away from any prevailing winds, with the slope.

You must bear this in mind when you choose which end to start sheeting; and if sheets are to be joined end to end, fix the bottom row first. Lay the first sheet at right-angles to the supporting purlins, at one end of the structure. Drill screw holes through the first corrugation on the non-jointed side to both end rafters and all purlins; on a standard, 1.8m long sheet this should mean at least four fixings. Note that the holes should run through the crest of the corrugation. You may find that there is not enough support beneath a crest for you to drill without distorting the sheet.

In this case, mark the positions of all the fixing holes and turn the sheet over, you will find that the crests have become valleys, and are easy to drill through. After drilling turn the sheet back again and fix through the first corrugation, taking care not to overtighten. Continue in this way along the sheet, drilling and screwing at every third corrugation, but do not yet fasten the last corrugation.

Now lay the next sheet on the structure, lap its first corrugation over the last corrugation of the preceeding sheet, and fasten the two together. Repeat the process for subsequent sheets, if necessary completing any sealing and fastening work as you go. If there is to be an upper layer of sheeting, it must overlap the other by at least 150mm and by twice as much if the roof slope is less than 10°. You must remove the topmost row of fixings on the lower sheets before fixing the upper ones in place.

Replacing single glazing pane windows to double glazing is a cheaper way to insulate your home, especially if you don’t like having PVCu windows and doors.

Plastic frames windows and doors,even thought they are virtually maintenance free, are considered to be in bad taste, and many people would rather have wooden framed windows and doors. Replacing the windows and doors with new – double glazed units, can be very expensive, around £2000 per (normal sized) window. If you have sash windows, the cost is even higher.

Single glazing can be replaced with double glazing if the frame and the structure of the windows and doors allows for a thicker glazing unit to be fitted. Sometimes the doors can’t accommodate the double glazing thickness for security reasons, and if the window has a large pane – the structure/frame needs to be reinforced in order to support the weight of the new double glazed unit, which is double of the original glazing.

In most cases, the glazing putty that older windows have around the window panes needs to be replaced, and the best way to remove hard putty is by heating it up using a blowtorch or a heat gun. Removing the paint and beading in this way will damage the paint work, but in most cases, the windows and doors needs to be repainted in the first place.

Double glazing or triple glazing units/panes are made from glass window panes separated by air or gas filled space (sealed unit) to insulate the building from losing heat. It also soundproofs the windows and doors.

The efficiency of the double glazing is measured in U – value and the most popular sizes are the 12mm, 16mm or 20mm air or gas gap , with 4 mm glazing x 2.

Contact our London carpenters for a free quote.

Design considerations when building a new staircase

• The rise must not exceed 220mm (190mm on a common stairway) and 140-178mm is thought satisfactory.
• The minimum going is 220mm (230mm minimum for common stairs), but you should try for a 255mm-305mm maximum.
• The maximum pitch is set at 42° to the horizontal and the minimum pitch is 25° (maximum pitch for common stairs is 38°).
• Where any tread has no riser below it, as in open plan or open riser stairs, the nosing of each step must overlap the back of the step below by at least 15mm.
• The gaps between treads on an open riser stairway must be designed in such a way that a solid sphere, 100mm in diameter, will not pass through them.
• The ease with which a stairway may be climbed is dependent upon the proportional relationship between the going and the rise, resulting in the rule that states: for any parallel step, the sum of its going plus twice its rise must equal between 550mm and 620mm.
• There must be no variation in rise or going (parallel steps) for each step in a flight of stairs between consecutive floors.
• Any stairway having a total rise of 600mm or more must have a handrail and adequate guarding extending to 840mm above the pitch line. If the stairway exceeds lm in width, handrails are required for both sides.
• Ballustrading must be provided to a height of 900mm (1070mm if the staircase is common).
• Infill ballustrading under the handrails should have openings of such dimensions that a solid sphere 100mm diameter, will not pass through them.

Carpenters building a new timber staircase

A time lapse video showing the construction of new stairs, including a landing.

London Staircase Builders & Carpenters

Flat roof terrace & balcony

Replacing a roof lantern is not a straight forward job like replacing a roof window or a sky light.

In Europe, roofing can be a mixture of traditional roofing, and modern roofing, especially in areas where Building Control is a lot more liberal.

Old roofing

The best roof in the world could be this one ?

The British Museum

Worktop Installers

Worktop Installer

Worktop Fitters

Worktop Fitter

Kitchen Worktop Fitter

Kitchen Worktop Installers

Kitchen Worktop Fitters

Kitchen Worktop Installer

Worktop Installation

Worktop Replacement

The business was founded as the Yale Lock Manufacturing Co. in 1868 by Linus Yale, Jr., the inventor of the pin tumbler lock, and Henry R. Towne.The name was later changed to Yale & Towne.In the twentieth century the company expanded worldwide.

It established a British operation by taking over an existing business in Wood Street, Willenhall, the historic centre of the British lock industry, and became the major employer in the town. ‘Yale locks’ became the generic term in the UK for pin-tumbler household locks and keys, although Yale neglected the ‘service’ business and effectively gave away the lucrative aftermarket business in replacement key-blanks, which sold in the millions annually.

The British Yale became involved with the early motor industry and supplied locks to various manufacturers until the early thirties when the cheaper diecast-based lead-tumbler technology became available. Yale saw an unexpected (and unwanted) revival of activity in the motor trade from the sixties onwards when security fitters adopted its ‘M69’ window lock as a simple add-on fitment to prevent theft, especially on vans. This continued to the early nineties, when it was superseded by electronic devices.

The British Yale had continued to supply all lock requirements to Rolls Royce Motors until 1991, when there was an acrimonious parting. The British business had been sold by its parent to the Valor Company in 1987. After a further takeover by Williams Holdings, various sections of the Willenhall operation and outlying operation such as their diecasting foundry were closed. Ultimately this led to all work being outsourced to the Far East, and the entire Wood Street site was soon afterwards closed and demolished, after having employed generations of skilled local people.

The remainder of the British business was sold to Assa Abloy in 2000.The Yale Security subsidiaries produce fire alarm systems, burglar alarms and glass break detectors.

From July 2012 Assa Abloy started to relocate Yale from Lenoir City, Tennessee to Berlin, CT, to be completed by late spring of 2013, with the loss of about 200 jobs. The factory had been in Lenoir City since 1953 and at one time had over 1200 workers.

Garage doors are larger, heavier, more exposed, and because they open outwards, easier to damage than any other exterior or interior doors around the house. Garage doors have their own peculiar problems, many of which needs to be addressed in order to protect your home, and preserve its appearance. Garage doors fall into two distinct categories:

The traditional ledged and boarded or framed, side-hung wooden doors;

And a wide range of metal or wooden doors which slide, fold, or can be lifted into position by a series of guides or tracks.

Wooden side-hung doors are still by far the most common, even though they are more likely to need repair or replacement than metal one.

Side-hung doors

Side-hung garage doors are attractive and can easily be made to match your house, but they must be carefully maintained if they are to remain serviceable. Garage openings are usually about 2.1m wide by 2m high and the sheer weight of the doors can cause serious joint sag—making them difficult to open and close, and generally unsightly. Slight warping and twisting can often be cured with the doors in situ by forcing them against the twist. Do this with cramps, against a heavy object or a fixed board to provide the necessary leverage.

With more serious cases, remove the doors and cramp them against the twist on a flat surface. This alone may cure the problem, especially if you soak the timber first to make it more pliable. But if you still have no luck, fit some form of bracing while the doors are cramped.

In the worst cases, you must draw the door frame square with sash cramps and reinforce the existing mortise and tenon joints with adhesive or extra screws. For a more professional job, it is better to dismantle the offending frame completely and refurbish the joints. When you come to reassemble it , drill, glue and insert strengthening dowels to supplement the existing tenons. Whenever you remove a door, lay it flat and take out any glazed panels before starting work.

The carpenter must also remove any old bolts which no longer support the door effectively, or which impede your efforts to straighten it, and this can be a troublesome process— especially if the bolts are rusted. If you cannot loosen coachbolts with penetrating oil, try cutting a slot in the bolt head with a hacksaw so that you can use a large screwdriver. If this fails, drill into the head of the bolt with a twist-drill as near the size of the bolt shank as possible. Flatten the bolt head with a rough file so that the drill bit does not slip and damage the wood, then slowly drill through the head until it drops away.

When you have squared up the door so that its diagonal dimensions are identical, drill out any splintered or rotten wood from the old bolt holes and fill them with a hard-setting epoxy or resin filler. When this has set, redrill the holes so that you can screw new bolts into the door. Bracing In most cases the repairs described above will be enough to keep the doors intact. But because garage doors are much heavier than other doors, it is well worthwhile fitting additional strutting to prevent problems from recurring.

One way of doing this is to attach a metal bracing bar diagonally across the back of the door. Use a mild steel bar about 6mm thick and between 25 and 50mm wide, and run this from the top end of the stile on the hinge side to the bottom end of the stile on the shutting side. Make sure that the bar does not extend beyond the edges of the door, then secure it with a number of 8mm coach bolts at intervals along its length.

Some ironmongers and steel stockists will supply a bar cut and drilled to your specifications, although it may be less trouble to buy a plain bar and make the holes yourself. In this case use a centre punch to locate the position of the bolt holes. Drill the pilot holes with a 2.5-3mm twist drill, then drill the final bolt holes. If you are using a power drill, use it on a low speed setting and lubricate the bit with oil as you drill As an alternative you can use a bracing (or straining) wire to support the door. Like the steel brace, this runs from the top corner of the hinge stile to the bottom corner of the opposite stile.

A screw-tightening device (similar to the bottle screws used to tighten the mast stays on sailing craft) lies diagonally on the door; when tightened, this lifts the bottom of the closing stile and keeps it clear of the floor when the door is re-hung. To prevent the door warping, cut notches in the corners of the stiles so that you can run the wire down both sides. Use staples to hold the wire in place. You can then re-hang the door and adjust the tensioner until the door hangs properly.

Although you can use ordinary fencing wire and a tensioning device available from a hardware store, a ship’s chandler will stock wire cable and a bottle screw adjuster that will do an equally good job. And bottle screws have the additional advantage that, being designed for a salt-water environment, they tend to resist corrosion more effectively. A less unsightly preventive measure is to fit a wheel castor to the bottom of the shutting stile. This will take the weight of the door when it is opened and closed, at the same time lifting the bottom edge off the ground. Remove the door to fit the castor, and screw the bracket to the rail rather than to the comparatively weak end grain of the stile. If possible, choose a spring-loaded castor that will ride over the unevenness of your drive.

Door rot

One common cause of door sag is wet rot in the wood, and the weight of a garage door tends both to exaggerate and accelerate the effects. Bad cases of rot and door sag entail dismantling the affected door and replacing rotten sections in their entirety. Early signs of rot are blistering and bubbling in the paintwork. Determine to what extent it has taken hold by sticking the blade of a penknife into the suspect areas until you reach sound timber. The most commonly affected areas are the bottom rail, the ends of the stiles, and the edges of glazed panels.

In the latter case the cause is normally rainwater running down the glass and behind the beading or rebated edge of the panel. Having cut out and patched the rotted section, bed the glass in an ample amount of putty smoothed level
with the beaded edge to prevent the problem recurring. Efficient puttying is particularly important in cases where the glass is patterned or reinforced with wire mesh because water can seep through the joints with the beading. If the rot extends beyond more than one of the joints of the stile, you will have to replace the stile completely. Start by removing the door and placing it on a flat surface or two trestles.

Drill out any dowels or mortise wedges in the joints, using a wooden block to protect the edges of the timber. Then knock the stile outwards from the rails with a hammer so that the tenons on the rails separate from their mortises. Use a softwood block to prevent the hammer blows from damaging the stile itself. Work your way slowly from joint to joint until the stile is released, then measure up the tenons on the rails and cut corresponding mortises in the new stile.

Clean down the surfaces of all the joints in the new stile and knot and prime them before applying the adhesive and sash cramps. Use a waterproof adhesive —urea or resorcinol formaldehyde. Alternatively, you can saw through the stile immediately adjacent to the joints and chisel away the rotten wood from around the joint area before replacing it. If only one joint on the stile has rotted, you can cut out the rotted section and replace it with a new joint. To do this, cut through the stile immediately above the rotted section and chisel or prise off the damaged wood, being careful to leave the tenon on the adjoining rail undamaged.

Cut a new section 75mm longer than the piece you have removed, and finish the end of the replacement piece. Cut a joint in the stile above the damaged section to correspond with the replacement section. This creates a strong and durable scarf joint which can be secured with screws and dowels. Cut mortises in the other end of the replacement piece to accept the tenons in the stile. Again, knot and prime all the surfaces of the new wood, including the joints, and glue and cramp the new wood into position before fastening the scarf joint with screws.

For additional strength secure the mortise and tenon joint between stile and rail with a dowel and insert wedges against the tenons. Plane and smooth all the edges, then prime and paint them. Often the tenons on the lower rail suffer from rot. If both ends are damaged replace the entire rail, but if only one end is damaged you can replace it in the manner described above, or construct a ‘false tenon’ that is jointed into the rail and held with glued dowels.

Tongued-and-grooved boards on traditional ledged and boarded doors often shrink, leaving exposed gaps between them. This is not only unsightly but also allows water to enter and rot the timber. The effect can be most damaging where the panels shrink away from the stiles to form a crack in the paintwork—allowing water to enter and rot the stiles. The most frequent cause is insufficient seasoning and, in acute cases, the best thing to do is to replace the boarding, cramping the new panels tightly together as you do so.

Treat minor cases by scraping off the cracked paintwork down to clean timber with a shave hook and then forcing a flexible epoxy filler into the gaps. These fillers are elastic enough to take up considerable movement in the boards, but they will not adhere properly unless the timber is completely free of paint. Once the filler has gone ‘off’, rub down any rough edges and repaint the door. Repairing a rotten frame Frame damage generally occurs at the bases of the uprights, which are exposed and more likely to absorb water from the ground. Determine the extent of the damage as above by probing the timber with a penknife.

Cut out the damaged section well past the rot and chisel a lapped joint at the base of the timber which remains. Then cut a replacement piece of timber to match the frame and form a lapped joint at the top to mate with the one you have just cut. As door frames can be bought in standard sizes, to match most existing frames, you should have no trouble finding a compatible piece of timber.
Drill screw holes in the replacement section, both to secure the lapped joint and to allow for the timber to be screwed or bolted to the adjoining masonry. Then locate it in position and mark the positions of the holes in the masonry with a hammer and a long masonry nail or drill bit. Remove the replacement section, drill out the holes in the wall with a masonry bit, and insert wallplugs to take No. 12 woodscrews.

Alternatively use expanding wall bolts. Then prime the back of the replacement section and glue a piece of bituminous felt to the foot to prevent the rot from recurring. Before gluing and screwing the new section to the original frame, check that it aligns correctly and i f necessary insert blocks of wood behind it to take up any unevenness in the wall. Finally, screw or bolt the new section to the wall, screw and glue the lapped joint, and knot, prime and paint the timber before replacing the door. Seal the entire frame with a non-hardening mastic at the point where it meets the masonry: this will help prevent moisture attacking the joint from behind.

Alternatives to side-hinged doors

Not all wooden doors are side-hinged: there are designs on the market for folding, sliding, and up-and-over doors made in timber, and they all suffer from problems similar to those described above. Many others, however, are manufactured in galvanized steel, aluminium, or glass fibre. All of them, including the wooden doors, run in guides or a variety of lifting mechanisms so that they open into an unobtrusive position. Their most frequent problem, therefore, apart from those problems shared with wooden doors, is that the tracking or lifting systems may fall out of adjustment as the door frames start to rot, or if the garage itself starts to settle with old age. Procedures for repairing them will obviously vary from one design to another, but most manufacturers supply full fitting and constructional details which include maintenance and adjustment instructions. You can refer to these if you encounter any of the problems with the doors, frames, or tracks mentioned above.

Fire doors or Fire Check Doors are used in new buildings, loft conversions, house extensions, garage conversions, conversions,offices, industrial buildings, restaurants, shops, etc.

The doors are designed to withstand a fire for a limited amount of time, usually not less than 30 minutes, time considered to be the minimum needed for the evacuation of a domestic property like a ground floor flat. The more complex the building, the greater the need for fire resistance materials is. Kitchen doors, Staircase doors, Hallways doors, Loft Conversions fire doors, etc are considered to be very important in containing a fire and usually are 1 hour fire resistant.

Door furniture like door hinges, locks and door frames, door lining – are designed for fires.

Building Regulations [Part B Fire Safety ] apply for most refurbishments, renovations, new builds, conversions and sometimes the fire doors must comply with BREEAM and the Code for Sustainable Homes criteria, as well as procurement requirements for responsible sourcing of materials such as those provided by forest certification and chain of custody required under CPET regulations.

Ask our carpenters for a Quote.

http://www.planningportal.gov.uk/buildingregulations/approveddocuments/partb/