Housing joints are very useful in constructing drawers, door frames and partition walls, among other things: but they’re indispensable for fixing shelves neatly into uprights. The joint gets its name because the end of the shelf fits into a square-bottomed channel or ‘housing’ across the upright. A basic housing joint is as simple as that, and very easy to cut and assemble. What’s more, it’s ideal for supporting the weight of a shelf and its contents – it resists twisting, and it looks much more professional than the metal brackets or other fittings which can do the same job.
Such fittings are readily available and often easy to use, but if your design is modern, they’ll tend to spoil its clean lines; and if it’s traditional, they’ll naturally be inappropriate. They will never give the unobtrusive and craftsmanlike finish which you can obtain from carefully designed and made housing joints.
Types of housing joint
There are a few variations, and each has its own purpose. A ‘stopped’ housing joint is completely invisible; you can’t see the connection between shelf and upright at all, because (unlike the basic ‘through’ housing joint) its housing stops about 20mm (%in) short of the front of the upright. You can also cut out a step in the front of the shelf to allow it to fit flush with the upright just as in a through housing joint, and so get the best of both worlds.
A ‘barefaced’ housing joint is a little more complicated. You still slot the shelf into the upright – but this time you also cut away a step or ‘rebate’ across the end of the shelf to form a sort of tongue (with one ‘bare face’). So the housing into which it fits has to be correspondingly narrower than the shelf thickness. This type of joint is used at corners, where you can’t cut an ordinary housing; and its stepped shape helps to keep the structure rigid. It can also be used with the rebate in the upright where you want unbroken woodgrain across the top surface of the horizontal.
Strongest of all is the dovetail housing joint. For this one, the housing has sloping (undercut) sides, and the end of the shelf is shaped to fit -which means it can’t be pulled out sideways. This is an attraction where you expect furniture to come in for rough treatment, (eg, being dragged across the floor). However, it’s tricky to cut without power-tool assistance, and in practice the do-it-yourselfer will seldom find it really necessary.
It’s worth saying here that even the best-made housing joint is only as strong as the shelf. If you’re planning shelf storage, you have to think about what the shelf is made of, its thickness, its length and how much weight you want it to carry. A thin shelf bends easily, and it’s unwise to try to span a gap of more than 1,200mm (4ft), at the very most, without some support in the middle. Even then, a full load of books will cause sagging.
Making a housing joint
Even with hand tools, housing joints are among the easiest to cut. For a basic through housing joint, you don’t need to touch the shelf at all. You just mark out the position of the housing in the upright, cut down the housing sides with a tenon saw, and pare a gap between the back of each tread and the next riser and fill it with low-growing plants or herbs to emphasise the edge of each step and provide a natural look. On wide, shallow steps you can place plants in containers and even build in seating areas to give a view of favourite aspects or to catch the sun at particular times of the day.
Away the waste with a chisel and wooden mallet. The only difficulty, as in all carpentry, is to make sure that your marking, sawing and chiselling are always careful and accurate.
A stopped housing takes a little longer to cut, but only because you need to hollow out its stopped end first, to make sawing easier. You may also need to remove a small notch or ‘shoulder’ from the shelf, which is easily done with a tenon saw and perhaps a chisel too.
For a barefaced housing joint, the housing is cut in the same way as a basic housing. Cutting the rebate in the shelf is another job for tenon saw and chisel.
Using power tools
A power router is an integral tool with a chuck that accepts a wide range of special bits for cutting grooves and mouldings quickly and accurately. It saves a lot of time when making housing joints, and eliminates both sawing and chiselling. Or you can use a circular saw, setting it for a very shallow cut and running it across the upright where you want the housing to be – first clamping on a batten to act as a guide. Because the saw- blade is narrower than the housing you’re cutting out, you’ll need to make several parallel, overlapping cuts.
Putting it together
When you assemble the joint before glueing, to see if it fits, you may think that it’s too tight and you need to pare away wood from the housing or the shelf.
But be sure not to overdo this – and be careful where you remove it from. A shaving off the wrong place can allow the end of the shelf to rise or fall so that it’s no longer level.
If, on the other hand, the joint turns out to be very loose, you’ll need thin slivers of wood or veneer to pack it out.
For maximum tightness, strength and squareness, a housing joint should really be glued, then cramped together while the adhesive sets. Where a shelf or shelves fit between a pair of uprights, as usually happens, your best plan is to glue and cramp the whole structure up at once, so as to get it all square in one go. Use sash cramps (long bars of steel with two adjust-able jaws) and simply place the structure between them, with the shelf running along their length, and blocks of scrap wood positioned on the outside of the uprights to protect them from the pressure of the jaws. You’ll probably have to borrow or hire the sash-cramps. When using them, you need to check the structure constantly for square-ness, as cramping, unless done correctly, can cause distortion.
You can always reinforce a housing joint by nailing through the outside of the upright and into the endgrain of the shelf, concealing the heads by punching them in and plugging the holes with wood filler.
On the whole, screws are best avoided, since they grip badly in endgrain; but for a chipboard shelf you can use special chip-board screws – or ordinary wood screws each driven into a special plastic plug, or ‘bush’, which is pressed into a pre-drilled hole in the end of the shelf. You can disguise screwheads with plastic covers. /
TIPS FOR BETTER HOUSINGS.
– a cramped-on batten is useful as a saw guide
– a third saw-cut down the centre of a wide housing will help the removal of waste
• for short housings in narrow wood, set the piece on edge and chisel vertically for greater accuracy
• use a rule or try-square to check that the housing has a level bottom.
• for pairs of uprights, use the housings in the first to mark out those in the second: this will ensure a level shelf.
• a chipboard shelf can be secured with chipboard screws driven into special plastic plugs.