Garage roof replacement: new roofs for garages and extensions

What our garage and extension roofs includes

• Strip of the old felt, sheeting or tiles, with waste removed
• New joists, rafters and 18mm OSB3 or ply decks where the old frame has failed
• Firring strips to give the fall to the gutter or outlet
• Warm roof insulation with vapour control layer for converted garages
• Torch-on felt, EPDM rubber, GRP fibreglass or tiled coverings
• Lead flashing where the garage or extension roof meets the house wall
• Roof lights, lanterns and kerbs for extension roofs
• Fascias, soffits, guttering and downpipes renewed with the roof

Garage roof replacement: what we find and what we fit

Garage roofs are the forgotten roofs. They sit behind the house, take the weather from every side and get patched, not maintained. By the time water drips onto the car, the felt has split, the boards are wet and the joists have started to rot. Doyle Homes has over 25 years' experience of roofing and building work, and garage roof replacement is a job we price to the day.

Our reviews include new roofs on a shed and a garage, and a new roof on a garage and conservatory together with gutters, downpipes and structural repairs. We handle the whole package, so you deal with one family business and one 20 year written guarantee.

Flat garage roofs: the build-up that lasts

A flat garage roof lives or dies by its frame. Many older garages carry light joists at wide spans, which dip and pond water. We check the joist size and spacing against the span, replace undersized or rotten timbers and fix an 18mm OSB3 or ply deck over them, with firring strips giving the fall to the gutter. For garages converted to rooms, we add a vapour control layer and PIR insulation above the deck.

Then comes the covering. Three-layer torch-on felt suits most garages and keeps the price down. EPDM rubber suits a wide, plain roof, and GRP fibreglass suits roofs with lots of detail or regular foot traffic. The flat roofing page compares all three.

Pitched garage roofs, cement sheets and asbestos

Pitched garage roofs in tile are re-roofed like a house: strip, breathable membrane, treated battens, new tiles and ridge, with a dry verge where the gable allows. Where the garage is attached, we match the tile to the main roof and tie the two together with lead.

Many garages built before 2000 carry corrugated cement sheets, and some of those contain asbestos. If we see them, we stop and tell you. Sheets are never cut or broken by us, and removal goes to a licensed contractor, after which we build the new roof. You get a straight answer on day one, not a surprise on day three.

Extension roofs: flat, pitched and glazed

A new extension needs a roof that meets the house wall and takes rainwater away cleanly. We build the frame, deck and falls, fit the covering and dress it into the house with lead flashing so the junction is watertight. An extension flat roof with a glazed lantern or roof lights adds kerbs and upstands, and every one gets sealed into the waterproofing. Our photographs include a finished flat roof with a roof lantern.

Where the design calls for a pitched or lean-to extension roof, we frame it with new rafters and cover it in tile, slate or sheet to match. Doyle Homes also runs the surrounding building work through trusted surveyors, architects, plumbers and electricians, so the roof fits the project, not the other way round.

Converting a garage: roof insulation and ventilation

A garage turned into a room needs a roof that behaves like the rest of the house. We build a warm roof: a vapour control layer on the deck, PIR insulation board above it, then the waterproof covering. The room stays dry and the joists stay above dew point. Where a new ceiling has already boxed in the joists, we check ventilation and correct the details that would trap moisture.

Fascias, gutters and drip edges matter as much as the surface. A garage edge with no overhang pours water down the wall, so we fit a drip trim, a properly fallen gutter and a downpipe that discharges where it should. We coordinate with the surveyors, architects, plumbers and electricians we recommend, so the roof is finished when the conversion starts.

Garage roof replacement cost and timescales

Price follows the size of the garage, the covering, the frame and any extras such as insulation, roof lights and fascias. A single garage re-roof is a one to two day job once the deck is sound, and a double garage or an extension takes longer. Your quote carries a timetable and no hidden costs, and for a first idea of numbers see our flat roof cost guide.

Access matters on a garage behind a terrace or at the end of a narrow drive. We plan ladders, tower or scaffold access and material delivery in the survey, so the quote already covers them and nothing is added later.

We offer a free, no obligation quote, and we will beat any written quote. All work is backed with a 20 year written guarantee, and we are fully insured.

Garage roofers near you

We work from our Dunstable office across Bedfordshire, Hertfordshire, Buckinghamshire and North London. Local pages cover Luton, Bedford, Hemel Hempstead and Harpenden. Customers rate us 4.91 from 62 reviews on TrustATrader, 4.7 from 23 on Google and 9.63 from 73 on Checkatrade. Ring 01582 807949 to book a survey.

Signs you need us

• Sagging or dipping garage roof, or water pooling in the middle
• Damp stains on the garage ceiling or walls, or drips onto the car
• Felt split, curling or patched many times
• Corrugated cement sheets cracked, mossy or broken
• Rotten fascia boards and sagging gutters along the garage edge
• Daylight visible through the garage roof boards
• An extension roof leaking at the wall junction or around a roof light