This section is from the book "Spons' Mechanics' Own Book: A Manual For Handicraftsmen And Amateurs", by Edward Spon. Also available from Amazon: Spons' Mechanics' Own Book.
This is another extremely light, durable, and waterproof roofing material, which differs essentially from the 2 preceding substances in needing to be fixed to rafters or scantling, and requiring no boarding on the roof. It is a kind of cardboard treated with cuprammonium solution, and has become a recognized commercial article. It is made in rolls of continuous length, 54 in. wide, consequently, when fixing the full width of the card (to avoid cutting to waste), the rafters should be spaced out 2 ft. 1 in. apart from centre to centre, so that the edge of one sheet of card laid vertically from eaves to ridge will overlap the edge of the adjoining sheet 4 in. on every alternate rafter, and be there fixed with outside batten as specified below. For sides and ends of sheds, partitions, ceilings, etc., the uprights or timbers against which the adjoining sheets of the card are overlapped and fixed should be placed 4 ft. 2 in. apart from centre to centre, with or without an intermediate upright. In all cases the card must be fixed with outside wooden battens (2 in. by 1) and strong nails (or screws) driven through the batten and card to the rafter or framework. The card is thus gripped between the batten and the framework.
For ordinary roofing, the nails or screws should not be less than 2 1/4 to 2 1/3 in. long, so as to provide firm holding. Iron bands bolted or screwed through the card will serve in place of battens (when desired) for curved roofs, lean-to's, etc.
At every joint the edges of the adjoining sheets must overlap each other 3 or 4 in., and be fastened by outside batten, as above specified; by this method very secure fixing and waterproof joints are ensured. An occasional screw is also recommended. Each sheet for roof should be cut long enough to extend from eaves to ridge, allowing sufficient length, not only to permit an overlap at the ridge, but also for turning up under the eaves-boards, there to be secured by a batten as before described.
In small structures, where the span is inconsiderable, the card by preference may be laid from eaves to eaves in one length, without joint at ridge. The sheet or panel when in position may be tacked down, while the battens are being fixed as already described. Previous to fixing, the card, being in a contracted state when cut from the roll, should be exposed to a cold or moist atmosphere, say for 12 hours, or sponged on both sides with water, in order to obtain flatness of surface. The sharp edges of the ridge-piece or caves-boards round which the card is strained should bo chamfered off. When a large sheet or panel of the card is required, two or more widths can be joined by overlapping the edges of the card 3 in., and riveting them together with copper rivets, or sewing by strong needle and waxed or "Willesden" treated thread. When advisable to strengthen the edge, it can be bent over and then 6ewn or riveted, or a strip of the card made in the form of a clip can be sewn or riveted on the edge of the sheet. In all cases before a sharp bend is made the card should be placed in cold water for a few hours, or sponged with hot water on both sides, to prevent cracking.
The card may be painted or tarred, and thus will not corrode or blister, as painted wood or iron, but remain practically indestructible.
A rapid, easy mode of covering may bo named as follows: - Cut a length of card from the roll, grip each end between 2 battens firmly screwed together, and draw the sheet or sheets thus secured over a roof, ridge, rick, pole, or anything requiring protection, and make fast to the ground or other holding, and, when desirable, for such temporary and portable covering the edges of the card may be bound with "Willesden" webbing, and eyeleted to enable the sheet to be easily made fast by cords or ropes. Similarly, a piece or strip of "Willesden" canvas may be riveted or sewn on to the card at any place, and serve as a flap, or for any purpose where canvas may be required.
The "Willesden" card possesses great practical advantage, by the ease with which repairs may be effected without skilled assistance. In case of accidental damage, a piece of card may be placed respectively on inner and outer side of the damaged part, and then be sewn together by strong needle and waxed thread, or riveted with copper rivets, Referring to the illustrations, the solid lines represent woodwork, while the broken lines indicate the roofing card. Fig. 1350 is a view of a shed roof; Fig. 1351, cross section of shed; Fig. 1352, detail of ridge and eaves, with alternative ridge construction, showing the usual fixing for sheds; Fig. 1353, detail of ridge and eaves, when the roof is to be made airtight; Fig. 1354, detail section of the rafters.