Costa, KFC and drive-thru fit-outs
Disused buildings converted into national brand restaurants and drive-thrus, starting with GRP flat roofs and warm roofs to get each shell water tight before first fix, then the full internal fit-out.
Roofing carpentry · Spalding, Lincolnshire
Flat roofs, warm roofs and GRP
Flat roof carpentry across Lincolnshire, Cambridgeshire and Norfolk, on domestic extensions, industrial units and commercial fit-outs. Deck, falls, insulation and GRP from one contractor, so the building goes water tight and the next trade can start.
What we do
A flat roof is a joist set, a fall and a detail that has to be right.
Flat roofs get a bad name because they are usually built too quickly. The carpentry underneath decides whether the covering lasts: joist size and centres, firrings cut to a real fall, a deck laid tight, upstands and trims formed square, and outlets at the low point rather than wherever was convenient.
AJB Group builds the whole thing. Joisted decks with firrings for the falls, warm roof build ups with the insulation over the deck, Celotex board and GRP finishes, low pitch lean-to roofs, parapet and upstand detail, and strip and replace where an existing flat roof has given up. On commercial work it is often the first item on site, because nothing else starts until the shell is water tight.
Warm roof or cold roof is the first question. A warm roof keeps the structure inside the insulated envelope and takes most of the condensation risk out of the joist zone, which is why it is the usual specification on new work. AJB built two warm roofs on the KFC and Taco Bell conversion at Northampton, boarded in Celotex and finished in GRP.
Where the flat roof sits alongside pitched work, the same team covers both. See hand cut roofs and roof repairs and alterations.
Flat roof work
- Structure
- Joisted decks, hand cut, including six storeys up
- Falls
- Firrings cut to gradient, outlets set at the low point
- Warm roof
- Insulation over deck, Celotex boarded
- Finish
- GRP, laid by our own team
- Low pitch
- Lean-to roofs down to 5 degrees
- Edges
- Parapet walls, upstands and trims
- Replacement
- 68 sqm rip off and re-install at Ramsey
Where they have gone on
Water tight first, everything else after.
On commercial conversions the flat roof is normally the item that unlocks the programme. AJB is often on site before anyone else for exactly that reason.
KFC and Taco Bell, Northampton. A disused town centre nightclub turned into two restaurants. The first task was a GRP flat roof across the back to get the building water tight so first fix could start, followed by a second warm roof boarded in Celotex and finished in GRP.
Starbucks drive-thru. A disused Little Chef taken on with remedial roof works and a new flat roof section formed for the drive-thru window.
Four Winds, Ramsey. A 68 square metre flat roof ripped off and re-installed in GRP, as part of a conversion where AJB project managed the carpentry, brickwork and plumbing packages, working closely with.
Bourne Town Hall. New flat roofs across a building with eleven separate roofs, plus a rear lower lean-to pitched at 5 degrees to carry mechanical works and industrial units.
For main contractors and developers
Flat roofs sit on the critical path more often than any other roof type, because the internal programme cannot start until the shell is dry. AJB prices the deck, the insulation and the GRP as one package from drawings, so there is no gap between the carpenter finishing and a covering contractor arriving.
Commercial fit-out clients include Costa, KFC, Taco Bell and Starbucks sites, plus Apex Demolition on the NHS Hinchingbrooke staff accommodation build. CHAS accreditation, SMSTS certification and a retained health and safety consultant mean the pre-qualification pack is already in place. See commercial carpentry for the full package.
For homeowners
Most domestic flat roof work is either a new extension or a roof that has failed and is letting water in. Either way you get a free site visit, a written estimate and one point of contact for the structure, the insulation, the covering and the fascias and plastics around the edge.
If the flat roof is part of a bigger job, AJB can take the whole thing, including the brickwork and the other trades. That is what happened on the 5 metre by 5 metre rear extension at Ramsey, where the flat roof was one item on a much longer list.
Proof
Drive-thrus and a 68 square metre replacement.
Four Winds, Ramsey
A 68 square metre GRP flat roof ripped off and re-installed as part of turning an old bungalow into a youth behaviour centre, with AJB project managing the carpentry, brickwork and plumbing package.
Related roofing services: roof repairs and alterations, fascias, soffits and plastics, or back up to roofing carpentry.
Common questions
Flat roof questions
What is the difference between a warm roof and a cold roof?
On a warm roof the insulation sits above the deck, so the structure stays inside the warm envelope and the risk of condensation in the joist zone largely disappears. On a cold roof the insulation sits between the joists and the void above it has to be ventilated. We build warm roofs regularly, including two on the KFC and Taco Bell conversion at Northampton, boarded with Celotex and finished in GRP.
Do you lay the GRP as well as build the deck?
Yes. We have fitted GRP flat roofs to get commercial shells water tight, including the flat roof across the back of a disused nightclub converted into a KFC and Taco Bell in Northampton town centre, which allowed first fix to start, and a 68 square metre GRP flat roof stripped off and re-installed at Ramsey.
How do you build in the falls?
Falls are formed with firrings cut to the required gradient over the joists, or by building the deck to a designed slope. Standing water is what kills flat roofs, so the falls, the outlets and the upstand detail get set out at the start rather than corrected afterwards.
Can you replace an existing flat roof that has failed?
Yes. A 68 square metre flat roof at Four Winds in Ramsey was ripped off and re-installed in GRP as part of a wider conversion where we project managed the carpentry, brickwork and plumbing packages.
Do you build low pitch and lean-to roofs?
Yes. At Bourne Town Hall the rear lower lean-to was pitched at 5 degrees to carry mechanical works and industrial units, alongside new flat roofs elsewhere on the same building. Low pitch roofs are common on link ways, rear extensions and plant enclosures.
Can you take a flat roof on a commercial building in use?
Yes. Most of our flat roof work is commercial: getting a shell water tight so other trades can start. Named examples include KFC and Taco Bell at Northampton, Costa Coffee at Leeds, and a disused Little Chef converted for Starbucks where remedial roof works were followed by a flat roof section for the new drive-thru window.
Flat roof to build or replace?
Deck, insulation and GRP priced as one package. Send the drawings or book a site visit.