The Handyman's Pocket Book: Roofs.

The chief trouble that occurs in a roof is that of leaking, and the treatment depends almost entirely upon the type of roof.

SLATE ROOF.  Leakage here is generally caused by a cracked slate, and the most satisfactory repair is a new slate.  The removal of the old one is the first job, and the slating ripper shown in Fig. 1 is used to withdraw the nails.  It is passed beneath the slate until one of the slots engages the nail. when a sharp tap or pull will either break the head right off, or pull it bodily out.  Some slates are nailed near the top, others at the centre; and it is generally possible to feel where they are.  The old slate being removed another of that same size is obtained.  To fix it a metal clip is needed.  It can be cut from a piece of zinc, copper, or some other non-corrosive metal, and fixed by a single nail driven between the joint of the slates beneath as shown in Fig. 2.  The new slate is pushed up and the clip bent over to hold it.

When a considerable area is in a bad way and it is not practicable to re-slate it, a temporary cure can often be made by covering the whole roof with a somewhat weak mix of cement.  It should be worked well into the cracks and joints and allowed to set.  The work should be done on a dry day as otherwise pouring rain may wash away the cement before it hardens.  Another plan which is also of a temporary nature it to use roofing felt held down by battens.  Joints should run parallel with the ridge as far as possible, the top piece overlapping that below.  Holding-down battens run from eaves to ridge.  If joints must run vertically a very generous overlap - say 12 in. - should be allowed, and the top piece nailed closely.

TILES.  Flat roofing tiles hav a projecting piece on the underside at the top known as the nib, and its purpose is to hook over the tiling battens nailed to the rafters.  To replace a tile it is necessary to lift up the adjoining tiles and insert wedges beneath to hold them whilst the old tile is withdrawn (see Fig. 3.)  It is then replaced by a new one of the same size.  If the tile has been nailed it is more difficult to withdraw, though levering up the tile generally partly withdraws it.  A slating ripper (Fig. 1) can be used to pull out the nail afterwards.  Do not attempt to nail the new tile.  Corks are often used to hold tiles up.

If the leakage is general it may be caused by wind forcing water upwards, especially when the pitch is low.  A cure can sometimes be effected from within by using cement as shown in Fig. 4.  It is worked in with a trowel.  This cannot be done with a close-boarded roof.

Incidentally it is not advisable for an inexperienced man to attempt to work high up on a roof as a slip could be most dangerous.

In a lean-to roof a common cause of leaking is the falling away of the wall plate from the wall as in Fig.
5.  If the plate is at all loose nothing short of refixing to the wall likely to be of any use, and this may mean at least partial stripping of the covering.  It all depends upon what the covering is.  In any case there will probably be some accumulated dirt which has dropped in at the top, and this will have to be raked out.

As a rule the wall plate is held by screws entered into plugs in the wall.  Possibly these have corroded, or perhaps the plugs have worked loose.  The best way, of course, it to get the wall plate away to enable new plugs to be put in.  If this would involve much trouble and the wall plate is sound in itself, it may be possible to follow the idea in Fig. 6.  A hole is chopped in the wall plate, thus revealling the brickwork and enabling it to be plugged.  Generally, Rawlplugs are the best to use as only a small hole is needed.  A piece of wood larger than the hole is then made as at A, and a stout screw driven through it into the plug,  thus anchoring the plate.  It may be that the slope of the roof will not allow this to be done, and then the only plan is to remove the covering adjacent to the wall.  The idea may not be practicable at all in some circumstances, but on occasions it can save complete dismantling.

When firmly in position the covering can be replaced or renewed and a flashing of zinc or roofing felt added as at B, Fig. 5.  The mortar in the seam above is raked out and the flashing cemented in, a mix of 1 part cement and 2 parts sand being used.  Damp the seam with a brush and water before cementing.

Sometimes a cement fillet is run along between the wall and the roof, and, providing the wall plate is firm it should last reasonably well, but it is not so satisfactory as a proper flashing.

FELT COVERED ROOFS.  Apart from actual tears in the felt, the chief trouble is due to faulty fixing. Joints on sloping roofs should be horizontal as far as possible with at least a 3-in. overlap.  Corners should be turned right over and nailed on the underside.  In the case of a lean-to there must be a flashing into the wall.

Patching a felt roof is a make-shift at best,  but it can be handy as a temporary repair.  If the tear is near the edge it may be possible to work the patch beneath the felt from the edge.  It may even be practicable to insert it through the tear.  In any case when it is in position the felt around the hole is raised and a generous amount of a bituminous roofing compound worked underneath.  The edges are then fairly closely tacked down as at A, Fig. 7.  If it is impossible to insert the patch beneath it will have to be close-nailed on top, again with a good layer of the bituminous compound between (see B, Fig. 7).

GLAZED ROOFS.  These are found mostly in greenhouses, scullery extensions, and so on.  One common cause of leaking is the perishing of the putty.  If the whole thing is in a bad way the only satisfactory plan it to remove the glass, scrape out the old putty, and re-set in new putty.  When this is done remember to paint the rebates first with priming paint.  Possibly the trouble in local only and then the putty can be raked out locally and a new fillet worked neatly along to cover both glass and wood.  If in the raking out the bare wood is disclosed, prime it with paint before puttying.

Sometimes the leak is due to a crack or some other fault having developed in the wood.  One of the bituminous compounds in most useful in dealing with such faults because it takes up to any subsequent movement.  Generally the difficulty is in locating the crack and then reaching it.  It may be necessary to take out one or two panes entirely.

Water has a trick of running down, and so giving a false idea of where the leak is.  The best plan is to go beneath the roof after a heavy shower and, mounting a ladder, try to trace it.  Dampness often causes staining in the wood, and this can be a clue.  Having found dampness always look higher up to see whether it has merely run down.

When you have located the source of the trouble make a chalk mark around it, and go to the outside.  You then have a guide as to where to look.  Once again look higher up because it is quite possible that water will run down the rebate and emerge at a point lower than where it entered.