SKEW NAILING
There II be some situations where you cannot get at the end of the wood to use dovetail nailing. Here you must use skew nailing instead. This means glueing the two pieces securely together and then driving a nail into the upright piece of wood at an angle so it also penetrates the horizontal piece.
Put a couple of nails into each side of the upright so that they cross. To stop the upright moving, clamp a block of wood behind it or wedge it against something solid.
Wood Joints in Carpentry
JOINTING BLOCKS
Made from plastic, these are just sophisticated versions of the wooden blocks you can make yourself, and they’re used in similar situations. Their only real advantage is that they tend to give a neater result when you’re working with veneered or melamine covered chipboard, but only because they come in the right colours. There are basically two kinds to choose from.
The simplest is just a hollow triangular ‘block’ that comes with a snap-on cover to hide the screws. More complicated versions come in two parts. You screw one half of the block to each piece of wood, and then screw the two halves together using the machine screw provided. It’s essential here that both halves of the block are positioned accurately, and since the blocks vary from brand to brand in the details of their design, you should follow the manufacturer’s instructions on this point.
ANGLE IRONS JOINT PLATES
If still greater strength is needed, use either an angle iron or a corner repair bracket to reinforce the joint. These are really just pieces of metal pre-drilled to take screws and shaped to do the same job as a reinforcing block (the angle irons) or to be screwed to the face of the two pieces of timber across the joint (the flat T-shaped and L-shaped corner repair brackets).
In either case, bring together the pieces of wood to be joined, position the bracket, and mark the screw holes. Drill clearance and pilot holes for all the screws, then screw the bracket to one of the pieces before glueing the joint together and screwing the bracket to the second piece. They don’t look very attractive, so use where appearance isn’t important, ie, at the back of a joint, or where the joint is going
Fitting and Fixing in Carpentry
FIXING INTO CHIPBOARD
Because neither nails nor screws hold well in chipboard, how do you hold a butt joint together? The answer is that you do use screws, but to help them grip, you drive them into a chipboard plug. Chipboard plugs are a bit like ordinary wall plugs.
In fact, you can use ordinary plugs, but you have to be careful to position the plug so that any expanding jaws open across the board’s width and not across the thickness where they could cause the board to break up. The initial stages of the job are exactly the same as for the overlap joint – marking out, drilling the clearance holes, and so on. The difference is that instead of boring pilot holes in the second piece of wood, you drill holes large enough to take the chipboard plugs.
Pop the plugs into the holes, glue the joint together and drive home the screws. Incidentally, if you can’t use any sort of plug at all – for example, when screwing into the face of the chipboard the only way to get the screw to hold properly is to dip it in a little woodworking adhesive before you drive it home.
REINFORCING BLOCKS
The joints described so far are fairly robust, but if a lot of strength is needed it’s worth reinforcing the joint with some sort of block. The simplest is a square piece of timber. First drill and countersink clearance holes through the block and glue and screw it to one of the pieces you want to join so that it’s flush with the end. To complete the joint, glue the second piece in position, and drive screws through into that.
You can arrange for the block to end up inside the angle or outside it. Choose whichever looks best and is easiest to achieve. With the block inside the angle, you’ll have a neat joint and the screw heads won’t be openly on display. However, in most cases it means screwing through a thick piece of wood (the block) into a thin piece (one of the bits you want to join), so it’s not as strong as it might be. If greater strength is needed work the other way round, driving the screws through the pieces to be joined, into the block. You can neaten the result to a certain extent by using a triangular rather than a square block.
DOVETAIL NAILING & THE OVERLAP WOODWORK JOINTS
DOVETAIL NAILING
This is a simple way of strengthening any butt joint. All you do is grip the upright piece in a vice or the jaws of a portable work-bench, and glue the horizontal piece on top if it – supporting it with scrap wood to hold the joint square – and then drive in the nails dovetail fashion.
If you were to drive the nails in square, there would be more risk that the joint would pull apart. Putting them in at an angle really does add strength. The only difficulty is that the wood may split. To prevent this, use oval brads rather than round nails, making sure that their thickest part points along the grain. If that doesn’t do the trick, try blunting the point of each nail by driving it into the side of an old hammer. This creates a burr of metal on the point which will cut through the wood fibres rather than parting them. Once the nails are driven home, punch their heads below the surface using a nail punch, or a large blunt nail. Fill the resulting dents with wood filler.
Dovetail Joint hand cut
THE OVERLAP
This is the simplest of all and is one you can use on relatively thin timber. The example shown is for a T-joint, but the method is the same if you want to make an X-joint.
Bring the two pieces of wood together as they will be when joined, and use a pencil to mark the position of the topmost piece on the one underneath. To reinforce the joint, countersunk screws are best, so mark their positions on the top piece of wood, and drill clearance holes the same diameter as the screw’s shank – ttie unthreaded part – right the way through. The screws should be arranged like the spots on a dice to help stop the joint twisting out of square. Enlarge the mouths of these holes with a countersink bit to accommodate the screw heads, and clean up any splinters where the drill breaks through the underside of the wood. Bring the two pieces of wood together again using a piece of scrap wood to keep the top piece level.
Then make pilot holes in the lower piece using either a bradawl or a small drill, boring through the clearance holes to make sure they are correctly positioned. Make sure the pilot holes are drilled absolutely vertically, or the screws could pull the joint out of shape. Finally, apply a thin coating of adhesive to both the surfaces to be joined (follow the adhesive manufacturer’s instructions), position the pieces of wood accurately and, without moving them again, drive home the screws.
Woodworking & basic carpentry
Sawing square
One of the most useful – and easiest to make – aids to sawing is a bench hook. It’ll help you to grip the wood you want to cut, and to protect the surface on which you are working. You can make one up quite easily, by gluing and screwing together pieces of scrap timber. You also need the ability to control the saw, and there are three tips that will help you here. Always point your index finger along the saw blade to stop it flapping from side to side as you work. And always stand in such a way that you are comfortable, well balanced, and can get your head directly above the saw so you can see what you are cutting. You should also turn slightly sideways on.
This stops your elbow brushing against your body as you draw the saw back – a fault that is often the reason for sawing wavy lines. Starting the cut Position the piece of wood to be cut on the bench hook and hold it firmly against the block furthest from you. Start the cut by drawing the saw backwards two or three times over the far edge to create a notch, steadying the blade by ‘cocking’ the thumb of your left hand. Make sure that you position the saw so that the whole of this notch is on the waste side of the line.
You can now begin to saw properly using your arm with sort of piston action, but keep your left (or right as the case may be) hand away from the saw. As the cut deepens gradually reduce the angle of the saw until it is horizontal. At this point you can continue sawing through until you start cutting into the bench hook. Alternatively, you may find it easier to angle the saw towards you and make a sloping cut down the edge nearest to you. With that done, you can saw through the remaining waste holding the saw horizontally, using the two angled cuts to keep the saw on course. Whichever method you choose, don’t try to force the saw through the wood – if that seems necessary, then the saw is probably blunt. Save your muscle power for the forward stroke – but concentrate mainly on sawing accurately to your marked line.
Cleaning up cut ends
Once you have cut the wood to length, clean up the end with glasspaper. A good tip is to lay the abrasive flat on a table and work the end of the wood over it with a series of circular strokes, making sure that you keep the wood vertical so you don’t sand the end out of square. If the piece of wood is too unmanageable, wrap the glasspaper round a square piece of scrap wood instead and sand the end of the wood by moving the block to and from – it’ll help in keeping the end square.
Simple joints in woodwork and joinery
It’s often thought that only elaborate joints give good results in woodwork. It isn’t true. There are simple ways to join timber, and one of the simplest is the butt joint. It’s easy to make, can be used on natural timber or man-made boards, and it’s neat. What’s more, given the right adhesive and the right reinforcement, a butt joint can also be strong enough for most purposes.
The great thing about butt joints is their simplicity. You can use them on any kind of timber or man-made board, provided it isn’t too thin – not under 6mm. The only problem you will run into is where you are joining chipboard. A special technique is needed here to get the screws to grip. Although it is possible to simply glue two pieces of wood together, unless you add some kind of reinforcement the result won’t be very strong. So in most cases, the joint should be strengthened with either screws or nails.
The question is which? As a rule of thumb, screws will give you a stronger joint than nails. The exception is where you are screwing into the endgrain of natural timber. The screwthread chews up the timber to such an extent that it has almost no fixing value at all. Nails in this case are a much better bet.
Choosing the right adhesive for carpentry
Even if you are screwing or nailing the joint together, it ought to be glued as well. London Carpenters Robuild use PVA woodworking adhesive, as it will do the trick in most jobs, providing a strong and easily achieved fixing. This type of adhesive will not, however, stand up well to either extreme heat or to moisture; the sort of conditions you’ll meet outdoors, or in a kitchen, for example. A urea formaldehyde is the glue to use in this sort of situation.
Choosing the right joint
There are no hard and fast rules about choosing the best joint for a particular job. It’s really just a case of finding a joint that is neat enough for what you’re making, and strong enough not to fall apart the first time it is used. And as far as strength is concerned, the various kinds of butt joint work equally well.
Marking timber
Butt joints are the simplest of all joints – there’s no complicated chiselling or marking out to worry about – but if the joint is to be both strong and neat you do need to be able to saw wood to length leaving the end perfectly square.
The first important thing here is the accuracy of your marking out. Examine the piece of wood you want to cut and choose a side and an edge that are particularly flat and smooth. They’re called the face edge and face side. Next, measure up and press the point of a sharp knife into the face side where you intend to make the cut.
Slide a try-square up to the knife, making sure that its stock – the handle – is pressed firmly against the face edge. Then use the knife to score a line across the surface of the timber. Carry this line round all four sides of the wood, always making sure that the try-square’s stock is held against either the face edge or the face side.
If you wish, you can run over the knife line with a pencil to make it easier to see – it’s best to sharpen the lead into a chisel shape. Why not use a pencil for marking out in the first place? There are two reasons. The first is that a knife gives a thinner and therefore more accurate line than even the sharpest pencil. The second is that the knife will cut through the surface layer of the wood, helping the saw to leave a clean, sharp edge.
Loft Insulation
Lofts are usually dark, dirty places, so it’s advisable to wear some really old clothes, preferably ones you can throw away afterwards. Blanket insulation, especially glass fibre, can cause irritation to the skin, so you must wear rubber gloves when handling it.
It is also sensible to wear a simple mask to cover your nose and mouth as the insulation material is not only unpleasant but dangerous to inhale. Loose-fill is a dusty material and you’d be wise to wear a pair of protective goggles — as well as a mask-when laying this. You can buy a mask, with replacement lint filters, and the goggles, all of which are available from most DIY stores. You’ll need a good light to work by; a fixed loft light is best, but if there isn’t one, you could rig up an inspection lamp or even a table lamp.
Don’t, however, use a torch: you’ll have enough to contend with without having to carry and aim a light. Don’t use a naked flame because the risk of fire is high in the enclosed space of the loft. Be careful where you tread. The space between the joists-the ceiling of the floor below – is only plasterboard or, in older houses, lath and plaster, and neither will support your weight. Rather than balancing on the joists – especially when you’re carrying rolls or bags of insulation – it’s better to have a short plank or piece of chipboard to stand on, but make sure that both ends are resting on a joist without overlapping, or it could tip up under your weight, with disastrous consequences.
Before you start to lay the insulation you should remove any boxes or other items you have stored in the loft to give you plenty of room to manoeuvre: if there’s too much to take down from the loft you can shift it up to one end of the loft, lay the insulation in the free area, then move the boxes back again and lay the other half. Clean up the spaces between the joists using a vacuum cleaner with a nozzle attachment to enable you to reach awkward corners. If you don’t have one you can use a soft bristled broom or a hand-brush and a dust-pan, but you’ll stir up a lot of dust in the process. Use small pieces of the insulation material to block up any holes made in the ceiling for pipework to and from storage tanks.
Laying the insulation
Laying the blanket type of insulation is simplicity itself: all you do is to start at the eaves and unroll the blanket between the joists. On widely-spaced joists it’ll just lie flat on the loft floor but if the joist spacing is narrow, or irregular, you can tuck it down and allow it to curve up the sides of the joists. Cut or tear small pieces of blanket from the roll to fit very small nooks and crannies.
Butt up new rolls and allow for extra material at beams and pipes that are set at right angles to the joists. Cut the insulation and tuck it under the obstruction, then butt up the next piece to it. Don’t insulate under the cold water tank, which will be mounted on timber bearers at right angles to the joists: heat rising through the ceiling immediately beneath the tank will help to prevent the water freezing in very cold weather. The tank itself should be insulated, with glass fibre blanket or expanded polystyrene sheets all round and on top, or you can use a proprietary tank lagging kit, available from DIY stores.
If your tank is mounted high above the loft floor — usually to enable you to get a sufficient head of water for a shower unit – you can insulate underneath it. The whole tank should, in this case, be lagged. Cut a square of blanket to cover the top of the loft hatch cover and tack it in place, leaving an overlap to stop draughts getting into the loft space. If you’re laying one of the loose-fill materials you’ll have to stop it from falling into the wall cavity at the eaves. Place a few bricks on edge, or a panel of chipboard, between the joists near the eaves, to contain the granules. Empty out the bags between the joists, starting at the eaves, and use a specially shaped timber spreader (see Ready Reference) to spread it to the correct thickness. The loft space will be much colder after you’ve insulated it, so it’s particularly important that you lag any water pipes that pass through the loft
TYPES OF ROOF INSULATION
There are three types of loft insulation you can lay yourself:
• blanket insulation consists of rolls of glass or mineral fibre matting, 80 or 100mm (3 or 4in) thick by about 6 or 8m (20 or 26ft) long. It’s unrolled between the joists
• loose-fill insulation can be a granulated mineral called vermiculite, expanded polystyrene granules, mineral wool fibre or cellulose fibre, available in bags. It’s tipped between the joists and spread out to an even thickness -100mm (4in) forfibre types, 125mm (5in) for granular materials
• sheet insulation is either expanded polystyrene between the joists or rafters, or fibreboard, which is laid across the joists with loose-fill or blanket insulation underneath.
LEVELLING GRANULAR INSULATION To lay granular materials to the correct depth -100mm (4in) – make a timber ‘spreader’ from anoffcut of chipboard, which you draw along the joists. Ensure:
• the body of the spreader just fits between the joists
• the arms rest on the joists • the depth of the body is 100mm (4in) above the loft floor. If your joists are only 100mm (4in)deep, lay the material flush with the top of the joists.
HOW MUCH INSULATION
To work out how many rolls of blanket insulation you’ll need: • multiply the length by the width of the loft to get the number of square metres
• allow a little extra for insulating tanks and pipework.
Insulating the roof
About a quarter of the heat lost from an uninsulated house goes through the roof, and so some kind of roof insulation should be your first priority for saving money on heating bills.
Houses leak heat like a sieve. Up to 75 per cent of the warmth generated within the house finds its way to the outside world through the roof, walls, windows and doors, and this represents an enormous waste of energy and money. Insulation reduces the rate at which heat passes through the various parts of your house’s structure, by trapping ‘still’ air within the insulating material itself.
Still air doesn’t conduct heat much and so wrapping your house in suitable insulation serves the same purpose as putting a tea-cosy on a tea pot: the tea stays hot for far longer. The converse is true during the summer: the insulation bars the heat of the sun. About a quarter of all the heat lost from an average house goes through the roof, and this is a particularly easy area to insulate effectively. What you do is to put your insulation in one of three places: on the highest ceiling; on the loft floor; or on the inside of the roof itself. Insulating the loft floor is the simplest and most effective of these: you should insulate the ceiling where there’s no loft or the roof slope where the loft space has been converted into living accommodation.
Why you should insulate
The savings you can make by insulating your loft depend on whether there’s any insulation there already (it’s the first layer that’s most effective), how much you put in, and whether you can control or alter your heating system to take advantage of the insulation. The last point is particularly important: if you install loft insulation and leave central heating controls as they are with a thermostat in, say, the living room, the most noticeable effect will be warmer rooms upstairs rather than dramatically decreased fuel bills. If, however, you can lower the tempertures in upstairs rooms, or keep them the same as before, by fitting thermostatic radiator valves or by turning radiators down (or off), your house will lose less heat and your fuel bills will be lower. Types of insulation There are four main types of loft insulation you can use: blanket, loose-fill, sheet and blown fibre.
You can install any of the first three yourself but blown fibre must be installed by a roofing contractor. The most extensively used loft insulation material is rolls of glass fibre or mineral fibre blanket, which you lay between the joists of the loft floor. You can choose from either of two thicknesses: 80mm (just over 3 in) and 100mm (4in).
Although you’ll benefit in terms of warmer rooms by installing thicker insulation, the more you put in, the less cost effective it becomes. From a practical point of view thicknesses greater than 125mm (5in) will probably take the insulation over the top of the joists, making walking about or storing things in the loft rather difficult. To save storage and transportation space the material is compressed when rolled up and packaged but it regains its original thickness quite quickly when unwrapped. The most common width of roll is 400mm (16in). Lengths vary from brand to brand, but they’re usually about 6 to 8m (20 to 25ft) long. Some glass fibre insulation is available in 600mm (2ft) wide rolls for use in lofts with wider-than-usual joist spacings.
The 400mm (16in) width is the most suitable size for most houses and allows a little to turn up where it meets the joists. Joists are usually 400mm (16in) apart but they might be as much as 450mm (18in) or as little as 300mm (1ft). If you have narrow-spaced joists the 600mm (2ft) width is probably the best to use: you can cut a roll in half with a panel saw while it’s still in its wrapper. Working out how much insulation you’ll need is simply a matter of multiplying the length of the loft floor by the width to calculate how many square metres there are.
Blocked roofing gutters
Blocked gutters
Roof rainwater gutters may become by leaves or other objects. An overflowing gutter isn’t an instant catastrophe but, if neglected, it will cause dampness to the house walls. An inspection, removal of debris and a hose down of gutters should be a routine part of every householder’s maintenance of the roof and property. Roofers London Robuild
Fixing new roof guttering
The obvious first step is to assemble the various bits and pieces you need, and you can use the old guttering system as a model to decide what’s required. It’s best to measure up the length of the guttering itself, allowing a little extra to be safe.
At the end of the run furthest from the downpipe, fix a gutter support bracket as high up the fascia as possible, and about 150mm (6in) from the end. The fixings here, and elsewhere, are made with 25mm (1 in) screws. Choose ones that are galvanised to stop them rusting.
Insert a nail into the fascia board level with the bottom bracket. . At the other end of the run, 150mm from the downpipe, fix another nail, tie a length of string tightly between the two, and use a spirit level to check that this string is level. When it is, lower the second nail by the amount needed to ensure that the guttering runs downhill towards the outlet.
This ‘fall’, as it’s called, varies according to the type of guttering, so check the manufacturer’s recommendations. Usually, it is in the region of 5mm for every metre of gutter run. Once you’ve found the right line for the gutter, fix another bracket level with the lowest nail. The next job is to fix the next bracket 1m (39in) from the one at the downpipe end of the run, using the string as a guide to set it at the correct level. Use these two brackets to support a length of gutter with the downpipe outlet attached.
Exactly how you join the gutter to the outlet – or indeed make any other joins in the guttering – will vary from brand to brand. With some, you slip the ends of the components into a special jointing piece called a union, and clip the whole lot together. With others, one of the components will have a union built into its end. Now work your way along, building up the gutter run as you go and adding additional support brackets as required, again using the string as a guide.
In most cases, you will need a bracket every metre, plus one on each side of every join – though some ranges contain combined unions and support brackets. Check the manufacturer’s recommendations. The only problem you may run into is when you have to cut the guttering to length, either to go round a corner, or to finish the run with a stop end. Do the cutting on the ground using a hacksaw, making sure that you cut the end square. Any roughness left by the saw should be cleaned up with a file.
If you want to turn a corner, fix the corner piece before cutting the straight piece of gutter to length. You can then use it to work out exactly how long the straight gutter length needs to be. When cutting to finish at a stop end, it is usual to leave about 50mm (2in) of gutter projecting beyond the ends of the fascia. When you’ve finished the job and checked to see that all the joints are properly connected, take a bucket of water to the highest point of the gutter and pour it down. If the gutter doesn’t drain all the water then go back and check your work.