Flat roof replacement (GRP) in Basingstoke | Case Study

The brief

Heritage Build Co. was called to a house in Basingstoke where the flat roof over a rear extension had been leaking for several winters. The homeowners were tired of temporary patches and wanted the roof stripped back to the joists, the deck repaired where necessary and a long-lasting waterproofing system installed. The extension measured roughly 6.5 metres by 3.2 metres and included two existing rooflights and parapet walls on two sides.

We priced the underlay, temporary protection, battens and fixings from the roofer's schedule, making sure everything was on site before the old covering came off. Because the work was scheduled for late autumn, we also allowed for a fast response if the weather turned during the two-week programme.

The clients wanted the rooms below to stay dry and usable throughout. We liaised with Heritage Build Co.'s roofing contractor to confirm the strip sequence and arranged for the temporary DPM, battens and fixings to arrive before the old felt was lifted. That meant the roof would never be left exposed overnight.

• Client: Heritage Build Co.
• Location: Basingstoke, Hampshire (RG21, RG22)
• Project: Flat roof replacement (GRP)
• Duration: 2 weeks
• Star Hawk material cost: £200

The challenge

Flat-roof replacements have a narrow weather window, and this Basingstoke job was scheduled for late November when two consecutive dry days could not be guaranteed. Once the old felt was off, the joists and deck were exposed, so every sheet of temporary DPM, every batten and every fixing had to be ready before the strip began.

Access was awkward. The roof sat over a rear extension with no side entrance, so materials had to be carried through the house or lifted over the garage. The scaffolding was restricted to the rear elevation, and the front pavement had to stay clear for pedestrians. We chose small, manageable bundles that two people could carry through the kitchen.

The detailing added complexity. The existing rooflights and parapet walls meant the deck had to be cut neatly and the waterproofing turned up and over the brickwork. We supplied extra battens and fixings so the carpenters could adjust the framing without a second run to a merchant.

The homeowners had lived with leaks for several winters, so confidence in the supply chain mattered. Having the underlay, DPM and fixings on site before the strip meant the roofer could take advantage of the first dry window instead of waiting for a delivery.

Long-term performance depends on what sits underneath the membrane. By supplying sound battens, temporary DPM and the right fixings, we made sure the deck was ready to receive the GRP system and that the upstands would stay watertight. We also held a reserve of screws at the yard in case the carpenters found more rotten deck than expected.

The parapet walls were particularly important because they acted as gutters for the roof below, so any gap in the DPM turn-up would channel water back into the rooms. We marked the roll widths on the brickwork during the pre-start survey so the roofer knew exactly how much overlap was needed at each corner, and we supplied an extra half-roll of DPM to allow generous laps. Quality control was tight because the roof was being finished in cold weather. The torch-on felt had to be stored somewhere warm before use, and the DPM had to be kept clean and free of creases. We checked each roll before dispatch and replaced one that had been crushed at the edge.

Materials we supplied

Heritage Build Co. sent us the roofer's schedule and we priced the items we could supply efficiently. The pack was small but critical: without these materials, the roof could not be stripped safely. The quantities we supplied were:

• Roofing and membranes: 4 rolls of Torch on Roofing Felt, 2 rolls of Damp Proof Membrane (DPM).
• Fixings and hardware: 5 boxes of Galvanized Nails, 8 boxes of High Performance Wood Screws.

The four rolls of torch-on felt were sized to cover the upstands, the deck perimeter and any localised repairs where the GRP system needed a bituminous separation layer. The two rolls of DPM were for temporary weather protection during the strip and for any detailing where a secondary membrane was required.

The five boxes of galvanized nails covered the battens used to hold the temporary DPM and any timber repairs, while the eight boxes of wood screws were for fixing the new deck boards and any replacement joist hangers. We chose screws with a corrosion-resistant coating because the roof was low and shaded for part of the day.

We held the rolls in our yard until the weather forecast showed a usable window. Because Basingstoke is on our regular round, we could move the delivery at 24 hours' notice if rain threatened. The roofer collected the materials from site each evening to keep them dry and secure.

A reserve of one extra roll of DPM and two extra boxes of screws was kept at the yard against Heritage Build Co.'s account. That reserve was used when the carpenters found a section of deck that needed replacing and consumed more screws than expected.

Delivery and logistics

We structured the Basingstoke deliveries around the roof strip sequence. The first drop was the temporary protection: two rolls of DPM and the battens and nails needed to secure it. This arrived the morning the old roof was stripped, so the exposed joists could be sheeted each evening if rain threatened.

The second drop was the torch-on felt and the wood screws, timed to arrive just before the carpenters started trimming the rooflight openings and fixing any new deck boards. Because the felt had to be warm to handle properly in late autumn, we delivered it on a day when it could go straight from the van into the heated garage.

Each drop used a small van rather than a lorry. The van could park on the driveway without blocking the pavement, and the materials were carried through the house on protective boards. Empty rolls and packaging were collected on the return leg.

Communication was direct. Heritage Build Co.'s site manager had one contact at our trade counter and confirmed each drop the day before. When the forecast changed, we moved the felt delivery by 24 hours to avoid it sitting in cold rain. When the carpenters found extra rotten deck, we sent more screws the same afternoon.

Because the programme was only two weeks, there was no room for error. We checked the route and access on the first visit and made sure the driver knew to use the rear gate rather than the front door. That small piece of planning saved time on every subsequent drop.

The build

The two-week programme began with the scaffolding going up and the old felt being stripped back to the joists. The deck was inspected, and two areas of rotten board were marked for replacement. The temporary DPM was laid over the exposed joists each evening and secured with battens and nails from the first Star Hawk drop.

On day three the carpenters replaced the rotten deck sections using new boards supplied by Heritage Build Co. and fixed them with the wood screws from our second drop. The torch-on felt was then applied to the upstands and perimeter details where the roofer needed a bituminous layer before the GRP system went on.

The rooflights were carefully trimmed and reseated. The parapet walls were prepared with the DPM turned up and over the brickwork, and the wood screws were used to fix any loose fascia boards around the roof edge. The GRP laminate and topcoat were then applied by the specialist roofing contractor.

Throughout the build, the site manager checked the weather forecast each afternoon and decided whether to sheet the roof for the night. Because the DPM and fixings were already on site, these decisions could be made quickly without waiting for a merchant to open.

Building control did not need to inspect the roof itself, but the site manager kept delivery notes for the DPM and felt in case the warranty provider asked for evidence. The paperwork was filed with the guarantee documentation.

By the end of week two the roof was fully covered, the scaffolding was down and the homeowners had a dry ceiling for the first time in several winters. The programme finished on the agreed date despite a wet spell in the middle.

The result

The new roof is a seamless, watertight surface with neat trims and properly dressed upstands. The rooms below are dry, the rooflights sit cleanly in the new deck, and the parapet walls are properly protected. The homeowners have a long-term guarantee on the waterproofing and have already noticed the room feels warmer. They also commented that the kitchen extension, which had been damp and musty every winter, now smells dry and stays at a more even temperature, even on cold Basingstoke mornings.

Heritage Build Co. reported that the roof strip went more smoothly than similar jobs where materials had arrived piecemeal. Having the DPM, felt and fixings on site before the old covering came off meant the roofer could work within the weather window rather than chasing supplies.

The house stayed usable throughout. Materials were carried through the kitchen on protective boards, the garden was not turned into a storage yard, and the neighbours did not raise any access issues. The only disruption was the scaffolding, which was unavoidable.

Waste was minimal. The old felt went into the skip, empty DPM rolls and packaging were collected by the final Star Hawk van, and unused screws were credited back. The homeowners were surprised how little mess was left.

The Star Hawk material cost for this Basingstoke reroof was £200. For Heritage Build Co., the value lay in having the right underlay, protection and fixings available before the roof was opened, with no hidden haulage and no delays.

What we don't supply on a reroof

Our supply covered the torch-on felt, temporary DPM and fixings, but the main waterproofing system and several related items sat outside our range. The GRP laminate, resin, topcoat and trims were supplied and installed by Heritage Build Co.'s specialist roofing contractor. Scaffolding, edge trims and any leadwork were also sourced separately.

Rooflights, roof windows and associated flashings were supplied by a specialist fenestration company. Any structural timber repairs to joists or deck boards, and any insulation upgrades above the ceiling, were the builder's own supply. We listed these exclusions in the original quote.

Cost transparency

The Basingstoke Flat roof replacement (GRP) was costed from the structural schedule, with every line item priced before the first order. The materials Star Hawk supplied came to £200 and broke down as follows:

Category	Materials supplied	Cost
Fixings & hardware	5 boxes Galvanized Nails and 8 boxes High Performance Wood Screws	£170
Damp proofing	2 rolls Damp Proof Membrane (DPM)	£40

The remaining cost covered the scaffolding, roof tiles or slates, lead work, roof windows and labour supplied by the roofing contractor. This is the usual reroof split: we supply the battens, felt, nails and screws, and the roofer provides the weatherproof covering and access.

Why Basingstoke homeowners choose Star Hawk

Basingstoke is within our Hampshire delivery round, covering RG21, RG22 and the surrounding areas. That local coverage means we can often deliver small roofing packs the same day, which is useful when the weather window for a reroof is short.

We keep a range of vehicles, from small vans that can park on a residential driveway to larger wagons for bulk orders. On this Basingstoke job, the van was essential because the materials had to come through the house and the front pavement had to stay clear.

Our trade counter stocks the core roofing and fixing range, including torch-on felt, DPM, battens, nails and screws. Having those items on the shelf means a builder can call in the morning and have protection on the roof by the afternoon if rain is forecast.

Accountability matters on weather-sensitive jobs. If a delivery is wrong, short or damaged, we correct it on our own account rather than sending the builder to a manufacturer. On a reroof where a missed delivery can mean a wet ceiling, that single point of responsibility is valuable.

Most of our Basingstoke customers are builders, developers and homeowners who want a written quote on the items we supply, reliable stock and vehicles that suit residential access. If that describes your project, send your schedule through the quote builder and we will come back the same business day with a price and a delivery plan. Basingstoke reroofs on estates such as Chineham or Hatch Warren often need batten and felt delivered before the scaffolder arrives, and we can time that first drop to suit. We keep the roofing battens, felt and nails in stock at our yard, so a reroof started on a Monday can be protected before the first rain later in the week. Our Basingstoke round also carries ridge tiles, vents and lead substitutes when the roofer wants them from the same supplier, reducing the number of deliveries to a residential street.