Flat roof waterproofing in Tbilisi
First we find where the water comes from: the stain on the ceiling is rarely right under the damage. Then, after opening up the roof, we decide: a repair over the old layer or a new roof down to the slab.
Where a flat roof leaks
Water gets under the covering, travels along the screed and insulation and comes out wherever it finds a gap in the slab. In detail — eight causes of flat roof leaks.
- 01Water ponds on the roofThere is no fall to the drains, or the screed has sagged. Where water stands for days, the covering ages several times faster.
- 02Parapet upstandThe covering is turned up the wall by less than 250 mm or has come unstuck — water gets behind the edge and leaks along the outer walls.
- 03Drains and outletsClogged with leaves, no clamping flange, the connection to the drain isn't reinforced.
- 04Penetrations for pipes and air conditionersEvery fixing through the covering is a potential hole; sealant around pipes dries out in two or three seasons.
- 05Seams in roll materialsThe overlap is below spec or the seam isn't welded along its full length. From outside such a seam looks intact.
- 06Expansion jointThe slabs move, and a continuous covering over the joint tears. The joint needs its own detail.
New roof, repair, terrace
A roof built up from the slab
- WHEN
- A new building — or the old roof can't be saved: wet insulation, blisters over the whole area, a broken-down screed.
- WHAT WE DO
- On the slab: screed to falls, vapour barrier, insulation, geotextile and PVC membrane with hot-air welded seams. Parapets, drains and penetrations as separate details.
Over the old covering
- WHEN
- The old covering is sound and dry, the insulation is dry, there is a fall. We check this by opening up at the inspection.
- WHAT WE DO
- Cleaning, local repairs, primer, reinforcing the details, two coats of polyurethane-bitumen membrane and a UV-resistant top coat. No seams.
Under tiles and decking
- WHEN
- Leaks in the room under the terrace, tiles lifting, joints darkening.
- WHAT WE DO
- We lift the tiles, install waterproofing and a drainage layer, and relay the finish.
Three systems for a flat roof
The engineer writes in the report what suits your roof. If a repair over the old layer is possible, the estimate has two figures: repair and full replacement.
PVC membrane roof
- PVC membrane 1.5 mm
- Geotextile
- PIR / XPS insulation — thickness by calculation
- Vapour barrier
- Screed to falls
- Reinforced-concrete slab
- WHERE WE USE IT
- Large flat roofs: residential complexes, malls, warehouses.
- STRENGTH
- Seams are hot-air welded, large areas go up fast, and it combines easily with insulation.
- LIMITATION
- Not for vehicle traffic; a walkable roof needs a protective layer.
Roof repair: Baumerk polyurethane
- UV-resistant top coat
- Polyurethane-bitumen membrane, 2 coats
- Primer
- Old bitumen covering — kept if sound and dry
- Screed
- Reinforced-concrete slab
- WHERE WE USE IT
- Roof repair, terraces, balconies, complex details.
- STRENGTH
- Seamless; goes easily around pipes, ducts and antennas. According to the manufacturer, polyurethane-bitumen compounds can also be applied over old bitumen membranes — if they are sound and dry.
- LIMITATION
- We check the old layer by opening it up: adhesion, damage, compatibility; base moisture no more than 4%. The base is always primed.
Torch-on roof
- Top layer with granules
- Base layer
- Bitumen primer
- Screed
- PIR / XPS insulation — thickness by calculation
- Vapour barrier
- Reinforced-concrete slab
- WHERE WE USE IT
- Budget roofs, patch repairs, garages and annexes.
- STRENGTH
- Proven technology at an affordable price.
- LIMITATION
- Installed with an open flame; quality depends on the material grade and seam work. Service life — per the manufacturer's data for the specific series.
Apartment block roof leaking? Start with a report
The engineer finds the source, makes a control opening and gives a written report with an estimate. With this document the homeowner association or management company settles the matter at a meeting.
Roof questions
01Can you just fix the spot above the stain?
Usually not: water travels along the screed slope and through the insulation and comes out wherever it finds a way — often several metres from the damage. After a rain or two the stain comes back, sometimes in a new place. So we find the source first: inspection, water testing, a control opening.
02Do you need to remove the old covering?
Not always. If the base holds, we repair over the old layer — faster and cheaper. The engineer decides after opening it up during the inspection.
03What if the insulation under the covering is wet?
Then a repair over the top won't help: the new layer traps the moisture inside — in summer vapour lifts the membrane into blisters, in winter ice cracks the screed. It needs a tear-off down to the slab, new insulation and a new roof. We find wet insulation with a control opening at the inspection.
04Can the work be done in winter?
Depends on the system and the weather. Liquid compounds need a dry base — the manufacturer requires moisture below 4% — and temperatures within the data sheet. We agree the work window in the estimate.
05Do you work under contract and give a warranty?
Yes. A contract with a fixed estimate and dates, handover after a water test with a signed report, and the warranty on the work written into the contract. Materials carry the manufacturer's warranty per the batch certificate.
If you plan to do it yourself: which materials to use and how much to buy — in our guide on asbshop.ge.
Book a roof inspection
The engineer finds where the water comes from and gives a written report with an estimate. Visit — 100 ₾, deducted from the estimate if you order the work.