Search for roof shingles and most of what you find comes from North America, where bitumen shingles cover very many houses. In the UK it is different. Houses here are covered in clay tiles, concrete tiles and slate, and shingles appear mainly on garden buildings: sheds, summerhouses, log cabins, garden offices and the odd porch. The product sold for those roofs is usually called felt shingles, felt tiles or bitumen shingles. This guide explains what they are made of, what roof they suit, how they are fixed and where they fall short, so you can tell whether they are the right covering for your outbuilding.
What felt shingles are
A felt shingle is a small tile cut from a reinforced bitumen sheet. The base is a fibreglass or polyester mat, coated on both sides with bitumen, and the top face carries a layer of mineral granules, usually in slate-grey, green, red or brown, that protects the bitumen from sunlight and gives the roof its colour. The tiles are sold in packs, in rectangular, hexagonal or rounded-tab shapes, and many have a strip of self-adhesive on the back that melts slightly in sun and glues each tile to the one beneath.
They are sometimes called asphalt shingles, which is the American name for the same type of product. On a UK garden building, felt shingles are a light, decorative alternative to a plain roll of mineral felt. They are not the same as the heavy, thick tiles used on American houses, and they are not designed for a main house roof here.
What roof they suit
Shingles are for roofs with a slope. They shed water because each course overlaps the one below, which only works if the roof is steep enough to carry water off before it can be driven back up under the tiles. Manufacturers state a minimum pitch for their product, and it is in the installation instructions, so check it before buying. A shed with a gentle slope of a few degrees cannot take shingles, and the right covering there is a mineral felt roll or a rubber membrane. A pitched shed, a gable-ended summerhouse or a log cabin with a clear slope can.
The roof deck matters too. Shingles need a continuous, firm base, and they are fixed to it with nails. Typical garden buildings have a boarded deck of tongue-and-groove or OSB, or plywood. A roof of widely spaced battens, as found on some cheap sheds, is not suitable without boarding first. Our guide to shed and outbuilding roofs compares shingles with the other common coverings on garden buildings.
How felt shingles are laid
The method is simple, but the detail makes the roof. The steps are these:
- Check the deck. Boards must be dry, flat and sound. Rotten or sagging boards are replaced first.
- Fit edge trims. A drip edge of metal or plastic is fixed along the eaves so water falls into the gutter and does not run back under the covering.
- Lay an underlay. A layer of felt underlay or a self-adhesive base sheet is laid across the deck as a second line of defence.
- Start at the eaves. The first row, called a starter course, is cut from shingles with the tabs removed and laid upside down so the adhesive strip seals the first full course.
- Work up in rows. Each course is nailed at the manufacturer's marked points, overlapping the one below by the stated amount, with the joints staggered so they never line up.
- Finish the edges. At the verges (the sloping edges of a gable end), shingles are trimmed and sealed. Where the roof meets a wall, a flashing keeps water out.
- Cap the ridge. Ridge pieces are cut from shingles, folded over the top and nailed so the nails are covered by the next piece.
The nails are the point where many DIY jobs go wrong. They must be galvanised or corrosion-resistant, with wide heads, and they must be driven flush, not crushed into the felt or left proud. Too few nails and wind lifts the tiles. Too many, or placed in the wrong spot, and the tile tears or the water finds a way in.
Measuring and buying
Work out the area of each roof slope by multiplying its length by its sloping width, not the width of the building underneath. The sloping width is measured up the rafter from eaves to ridge and is always longer than the plan width. Add the two slopes together and allow extra for cutting, because shingles are trimmed at the edges, the ridge and the starter course. Packs state their coverage, and the manufacturer's allowance for overlaps is already built in, so use their figure and not an estimate from the tile size.
Buy everything from one batch if you can. Colours drift slightly between production runs, and a replacement pack bought two summers later will rarely match. Buy the trims, adhesive, underlay and nails the maker recommends at the same time, because mixed components can undermine the product's warranty. Keep a pack of spares for repairs, stored flat and dry.
Edges, overhangs and rainwater
Garden buildings often have the shortest edge details of any roof. A roof that overhangs the walls by a few centimetres sheds water clear of the cladding, while one cut flush leaves the walls wet. Eaves need a drip edge so water leaves the roof and does not wick back along the deck. A small gutter and downpipe, or a water butt, keep the base of the building dry and stop splashes rotting the bottom boards. At the verges, the shingles should project slightly over a bargeboard or trim so rain does not run in behind them. Where the shed butts against a fence or wall, a flashing or a gap is needed, so that damp does not pass from one to the other.
Weather, temperature and sealing
Self-adhesive strips need warmth to bond. In cold weather the strips do not seal, and tiles laid in winter can stay loose until a warm spell. If you are laying in a cold month, some installers add a dab of bitumen adhesive under each tab, as the maker recommends. Hot weather has its own risk, since tiles become soft and easy to scuff, so walking on them has to be done carefully. Wind is the biggest enemy before the strips have bonded, which is why shingles are best laid in mild weather, and tiles must be kept flat in storage and not left folded or stacked for long.
How long they last, and how they fail
Felt shingles are a light-duty covering. They are cheap and easy to fit, but they are thinner than the shingles used on houses abroad, and their life is correspondingly shorter. The mineral surface wears, the tabs curl and lift, nail heads work through, and moss builds on shaded slopes. Tiles at the ridge and eaves go first, since they take most of the wind. Individual shingles can be replaced, though a roof with widespread curling or granule loss is nearing the end. Our answer on how long shed felt lasts covers the equivalent for roll felt.
The cause of failure is often below the tiles. A deck that was damp when covered, a shed with no ventilation, or a roof with a leaking edge can rot the boards, and the first sign is a spongy patch. Condensation inside a garden room with a warm interior and a cold roof can do the same, so a roof over a heated or lived-in room needs proper insulation and ventilation.
Shingles compared with other coverings
| Covering | Best suited to | Main drawback |
|---|---|---|
| Felt shingles | Pitched sheds, summerhouses and cabins | Needs a pitch and a firm deck, light-duty life |
| Roll mineral felt | Low-pitch sheds and small flat roofs | Plain appearance, can split at laps |
| EPDM rubber | Flat or near-flat garden rooms | Needs a smooth, clean deck and careful edges |
| Profiled sheets | Pitched stores and workshops | Noisy in rain, condensation underneath |
| Slate or tile | Substantial garden buildings, houses | Weight needs a strong frame |
Using shingles on a garden room
A garden room or home office raises the standard. These buildings are heated, furnished and used, so a leak or condensation costs more than in a shed. The roof needs a vapour layer and insulation, and the felt shingles go over a boarded deck above them. The simplest arrangement is a warm roof with rigid insulation above the deck and the shingles fixed over it, but fixing through the insulation needs the right system and nail lengths. If the building is large or close to a boundary, you may also need to check planning and building control rules. The garage roof options guide shows the wider choices.
Trees, moss and wildlife
Garden buildings sit under trees more often than houses do. Leaf litter and damp shade encourage moss, and moss holds moisture against the tiles and lifts their edges. Brush off moss gently with a soft brush rather than scraping it, and avoid a pressure washer, which strips the granules. Birds and small animals may also nest under the eaves of a shed, and nesting birds and bats are protected, so if you find either, delay the work and check what applies before disturbing them.
Repairing a shingle roof
Small repairs are easy. A lifted tab can be re-stuck with a dab of bitumen adhesive, and a split or missing tile can be replaced by lifting the course above, removing the nails, sliding in a new shingle and nailing it back. Use matching tiles where you can, and keep a spare pack from the original job, since colours vary between batches. A ridge that has blown off should be refitted with nails under the next piece. If many tiles are lifting, the problem is probably the fixing, the weather at the time of laying or the age of the roof, and a replacement may be better than a string of repairs.
Getting the job done
If you have a shed or garden room that needs re-roofing, we can survey it and tell you whether shingles, felt or a membrane suits the roof. We photograph what we find, give a fixed written quote and stand behind the work with a ten-year written guarantee on our workmanship. See the garage roof replacement in Basingstoke page for the full range of outbuilding roofs we cover, or ring 01256 213956.
