An ageing flat roof can leave you facing an expensive decision. Perhaps the felt has started cracking, a joint has opened, or a damp patch has appeared on the ceiling. You want a lasting repair, but replacing the entire roof means labour, waste removal and disruption.
Before committing to a replacement, find out whether the existing roof can support a new waterproofing layer. If the structure remains sound and the surface is suitable, Lava 20 can extend the roof’s useful life while avoiding an unnecessary strip-off.
Available from Dooley Timber, Lava 20 is a liquid-applied waterproofing system for new roofs and refurbishment projects. For homeowners with a tired but repairable flat roof, it offers a practical route to renewed weather protection.
Age alone does not tell you whether a roof needs replacing. The condition of its different layers matters more.
A flat roof includes the supporting structure, a deck, waterproofing and, depending on its construction, insulation and other layers. The exposed covering may deteriorate while the deck underneath remains serviceable. In that situation, renewing the waterproofing can preserve materials that still have useful life.
A roof with rotten decking, saturated insulation or structural movement needs a different approach. Covering those problems leaves the underlying damage in place.
Arrange an inspection if the roof sags, leaks repeatedly, or shows signs of deterioration beneath the covering. Avoid walking onto a roof to test whether it feels soft. A competent roofer can assess its condition and advise whether local repairs, an overlay or replacement makes sense.
A local repair may suit an isolated defect when the surrounding waterproofing remains in good condition. Examples include a damaged section around a penetration or a small area of failed detailing.
Refurbishment becomes worth considering when weathering affects a broader area, but the existing roof can still provide a sound base. Applying a compatible waterproofing system across the roof creates continuous protection rather than leaving a collection of separate patches.
Replacement may be necessary where damage extends through the roof build-up, the covering cannot support an overlay, or drainage defects require substantial reconstruction. It can also provide an opportunity to improve insulation.
Ask whoever inspects the roof to explain which layers have failed. That explanation helps you compare quotations and understand whether removing the whole roof is justified.
Lava 20 is a single-component polyurethane liquid waterproofing membrane. Once cured, it forms a seamless, flexible waterproof covering. Its liquid format allows it to follow the roof surface and accommodate details that require careful cutting and joining with sheet materials.
The product is designed for both new and existing surfaces. Dooley Timber lists applications including felt, asphalt, concrete, timber, metal, GRP and certain single-ply membranes. Each surface needs the appropriate preparation and system specification, including primer and reinforcement where required. See the Lava 20 product information for the listed applications.
For a suitable existing roof, this means the waterproofing can be renewed without removing every layer beneath it. Confirm the existing material before ordering, particularly if previous owners have applied unidentified coatings.
Retaining a serviceable roof avoids the work involved in stripping it back. Depending on the project, that can reduce removal labour, disposal requirements and the amount of replacement material needed.
It can also reduce disruption around the house. A refurbishment generally involves less demolition, although access, preparation, repairs and curing still need planning.
Lava 20’s flexibility and UV resistance make it suited to exposed waterproofing applications. The seamless finish removes joints within the newly applied membrane, while the liquid application helps installers work around outlets, corners and changes in level. The manufacturer describes these properties as benefits of the cured coating.
For homeowners, the benefit is preserving a roof that can still perform once its waterproof protection has been renewed. The savings depend on the roof’s condition and the preparation required, so compare complete project costs before deciding.
Lava 20 can suit a capable DIY homeowner working on a suitable, safely accessible roof. Application uses familiar tools such as brushes and solvent-resistant rollers, rather than requiring a torch-applied installation or mixing of resins.
However, applying the coating is only one part of the job. Identifying the surface, repairing defects, selecting the correct primer and completing the details all affect the result.
A small roof with straightforward edges may be manageable for someone experienced in exterior maintenance. A larger roof with several outlets, rooflights, awkward access or uncertain damage deserves professional assessment.
Plan safe access and edge protection before buying materials. Never assume an old roof or rooflight can support your weight. Follow the product’s safety data sheet for protective equipment, handling and ventilation requirements.
Preparation determines whether the new membrane bonds to the existing surface. Allow enough time for this stage instead of treating it as a quick clean before coating.
The manufacturer requires a clean, dry surface free from moss, dust, grease, rust and loose particles. Remove contamination using methods appropriate to the roof’s condition, then allow the surface to dry fully. Cleaning must not damage an already weakened covering or drive water into the roof.
Repair loose material and defective areas before applying the system. Investigate blisters, open joints and recurring leaks rather than coating over them without understanding their cause.
Check gutters and outlets too. Clear debris and address drainage problems. A waterproof membrane does not correct an inadequate fall or a blocked outlet.
The manufacturer’s application FAQs explain the preparation requirements and confirm that existing surfaces must be sound before coating.
Different roofs need different preparation. A coating that adheres well to one material may require a specialist primer on another.
Check the current Lava 20 guidance for the exact surface you intend to coat. Previously treated roofs may also need an adhesion test or technical advice before proceeding. Tell your supplier about any old coatings, sealants or repairs you can identify.
Reinforcement is particularly relevant to felt and asphalt refurbishment. The manufacturer specifies matting for these surfaces and describes embedding the reinforcement within the liquid system. Joints, cracks, overlaps and vulnerable details also require attention.
Buy the compatible components specified for your roof. Substituting a general-purpose sealant or omitting reinforcement can compromise an otherwise carefully applied coating. Ask Dooley Timber to help identify the materials you need before placing your order.
Start with the current application instructions for your chosen roof build-up. Confirm the required coverage, layer thickness, reinforcement method and curing arrangements before opening a container.
Plan the work so that details receive proper attention. These include upstands, where the roof meets a wall, along with outlets, edge trims, corners and pipe penetrations. The Lava range includes products for complex details and vertical surfaces; their suitability depends on the specification.
Apply the membrane evenly using the recommended tools and embed reinforcement as directed. Avoid spreading the material too thinly to cover extra area.
The manufacturer describes wet-on-wet application for reinforced systems, but timing and preparation requirements depend on the method and any delays between stages. Follow the instructions supplied for your project rather than combining advice from different application methods.
Measure the whole treatment area, including upstands and details. A roof’s footprint alone may underestimate the amount of material required.
Dooley Timber lists approximate coverage of 10 square metres per 25kg container at a finished thickness of 2.5mm. Surface texture, absorbency and the specified system can affect consumption. Use the current product guidance to calculate your order and allow for the roof’s actual condition.
Choose a suitable weather window. The roof must meet the specified surface and temperature conditions, with enough time for application and curing. The manufacturer recommends dry weather with no rain forecast for several hours.
Curing varies with conditions, thickness and catalyst use. Check the instructions before adding an accelerator, and plan how you will protect the work while it cures.
A correctly specified and applied refurbishment can extend the useful life of a suitable roof. The outcome depends on the existing structure, preparation, installation quality, exposure and maintenance.
Avoid assuming that a product name or warranty promises a fixed additional lifespan for every roof. If warranty cover influences your decision, request the current written terms and confirm the installation requirements and eligibility for your project.
After completion, inspect the roof periodically from a safe position. Keep drainage routes clear and arrange checks after damage or severe weather. Give particular attention to outlets and junctions, where debris and later building work can affect waterproofing.
If your flat roof remains structurally sound, Lava 20 offers a practical way to renew its waterproof protection and postpone a full replacement. Careful preparation and the correct system give you the best basis for a durable result.
Before ordering, gather the roof measurements, photographs and details of the existing covering. Note any leaks, previous repairs and areas where water collects.
Explore the Lava 20 waterproofing system from Dooley Timber, then confirm the primer, reinforcement and accessories required for your roof. With those decisions made, you can price the complete refurbishment and plan the work.
