Core sampling. Know exactly what is under the membrane before you specify the work.
Roofcheck provides roof core sampling on commercial and industrial flat roofs across the UK for facilities managers, property owners, managing agents and contractors who need to know how a roof is built and whether it is wet. Each core confirms the waterproofing layers, insulation, vapour control layer and deck, and is sealed watertight afterwards.
Core sampling for commercial roofs
A core sample removes a small, controlled section of the roof so the whole build-up beneath the membrane can be examined, layer by layer, all the way down to the deck.
It confirms what the roof is made of and whether water has got into it, so options such as an overlay can be judged on fact rather than assumption.
Before an overlay or refurbishment
Confirms whether the existing build-up can stay and be overlaid, or needs stripping back.
Confirming moisture readings
Shows whether areas flagged by moisture mapping or thermography are actually wet, and how badly.
Where there are no drawings
Establishes the build-up and deck type where records are missing or unreliable.
Diagnosing defects
Helps explain blistering, loss of adhesion or suspected wet insulation.
Checking the deck
Shows the condition of the top of the deck, including corrosion on steel decks.
Pricing a replacement
Gives contractors the layers and thicknesses they need to price strip-out and replacement.
What a core sample shows
Every layer of the roof, measured and photographed, down to the deck.
What it shows
- The waterproofing layers, and how many earlier roofs lie beneath
- The insulation type, thickness and condition
- The vapour control layer
- The deck type and the condition of its top surface
- Whether water has got into the build-up, with moisture measured
- How each layer is attached
Limitations
- Each core shows only a small area, so cores are used alongside moisture mapping or thermography to judge the whole roof
- It is intrusive: the membrane is opened at each core, which is sealed watertight straight afterwards, and any roof warranty is checked first
How core sampling works
Pre-survey review
Drawings, earlier reports and any moisture readings are reviewed to choose where the cores should go.
Taking the cores
Small sections are cut through the roof, down to the deck, at the agreed locations.
Recording each layer
Every layer is measured, photographed and described, and the moisture in the insulation is measured.
Sealing and report
Each core is sealed watertight, and the results are issued online and as a PDF.
Manage your core sampling surveys online
Approve quotes, follow every survey and open reports in one place, then share them by link so everyone works from the same information.
- Core 1
- Membrane over earlier felt, wet insulation
- Core 2
- Single membrane, dry insulation, retain
- Core 3
- Dry insulation, surface corrosion on steel deck
A report you can act on
Every core is located on a plan of the roof, with each layer measured and photographed.
- The location of every core on a plan of the roof
- Photographs and measurements of each layer
- Insulation type, thickness and moisture level
- Deck type and condition
- Online and as a PDF
Questions about core sampling
What does a core sample show?
The waterproofing layers and how many earlier roofs lie beneath, the insulation type, thickness and condition, the vapour control layer, the deck type and condition, and whether water has got into the build-up.
How many cores are needed?
It depends on the size of the roof and how consistent the build-up is. Cores are placed where they tell you the most, often guided by moisture readings, and your quote sets out how many and why.
Do I still need cores if I have had a moisture survey?
Usually, yes. Moisture mapping and thermography show where the roof may be wet. Cores confirm it and show what the roof is actually made of.
Can a core sample show whether the roof can be overlaid?
Yes. It confirms the existing build-up and whether the insulation is wet. Wet insulation generally has to come out before a roof can be overlaid.
Why does wet insulation matter?
Insulation that holds water loses its ability to insulate, and water trapped under the membrane can damage the deck over time.
Is core sampling intrusive?
Yes, but only at small, agreed locations. Each core is sealed watertight straight afterwards with compatible materials, and any roof warranty is checked before cores are taken.
What roofs can be cored?
Flat roofs of every common type, whether single ply, felt, liquid applied or asphalt, on concrete, metal or timber decks.
What is needed from the client?
Safe access to the roof, any drawings, earlier survey reports or core records, and warranty details so cores can be taken without affecting cover.
How much does core sampling cost?
Cost depends on the number of cores, the roof build-up and access. Call 0113 868 0097 or start a quote online with the approximate roof area, and you’ll receive a written quote.
Get a core sampling survey
Whether you’re investigating a problem or planning ahead, we’ll help you choose the right survey for your roof. Get in touch for a free quote.
Free quote
A few details about the building and what you need to find out. It commits you to nothing.
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