Single ply and liquid

EPDM deck adhesive and contact adhesive quantities

L_{d} = \frac{A}{c_{D}}

A_{c} = \frac{P h_{u}}{1000}

L_{c} = \frac{A_{c}}{c_{C}}

n_{d} = ⌈ \frac{L_{d}}{V_{d}} ⌉

n_{c} = ⌈ \frac{L_{c}}{V_{c}} ⌉

where
$L_{d}$: deck adhesive (litres)
$A$: flat deck area to bond (m²)
$c_{D}$: deck adhesive coverage (m²/litre)
$A_{c}$: contact-bonded area (m²)
$P$: length of upstands and perimeter (m)
$h_{u}$: height of the contact-bonded strip (mm)
$L_{c}$: contact adhesive (litres)
$c_{C}$: contact adhesive coverage, both faces (m²/litre)
$n_{d}$: deck adhesive tins
$V_{d}$: deck adhesive tin size (litres)
$n_{c}$: contact adhesive tins
$V_{c}$: contact adhesive tin size (litres)

Explain this equation

Works out how much deck adhesive and contact adhesive an EPDM roof needs, and how many tins to buy.

The flat deck is usually bonded with a water-based adhesive at coverage c_D, so litres are the area divided by the coverage. Upstands and the perimeter are bonded with solvent contact adhesive on both faces; that strip area is its length P times its height h_u (converted from millimetres). Dividing each volume by the tin size and rounding up gives the tins.

Coverage rates are area per litre, so quantity is area divided by rate.

Sense check: 12 m² at 2.8 m²/l is about 4.3 litres, one 5 litre tin. 7 m of 150 mm upstand is 1.05 m², about 0.7 litres of contact adhesive.

Watch out: rough or absorbent decks use more. Take coverage from the maker's data sheet and keep the contact adhesive for its stated open time.

Estimates the water-based deck adhesive for the main roof area and the solvent contact adhesive for upstands and perimeter details.

Enter your values to see the result.

Good to know

Coverage depends on product and deck. ClassicBond quotes 2.8–4 m²/litre for its water-based deck adhesive on timber decks and about 1.5–2 m²/litre for its contact bonding adhesive; Firestone RubberCover water-based adhesive is sold at about 5 m²/litre; Elevate (Firestone) BA-2012 bonding adhesive gives 2.35–3 m²/litre by roller, both faces combined. The defaults are the conservative ends of the ClassicBond ranges. Water-based adhesive is for horizontal decks; vertical upstands and edge details need contact adhesive.

Common mistake

Using water-based deck adhesive on upstands, or forgetting it cannot be used in cold or damp conditions. Use contact adhesive on vertical faces.

Limits

Smooth, sound OSB or plywood deck. Rough or porous substrates use more. Check the data sheet of the product you are using.

Sources

Results are calculations from the published methods and figures shown, and depend on the data you enter. Follow the roof covering manufacturer’s fixing specification, BS 5534, BS 8000-6, BS 6229, the Lead Sheet Training Academy guidance and Building Regulations. Wind uplift and structural design need a competent designer.

EPDM deck adhesive and contact adhesive quantities

Good to know

Common mistake

Limits

Sources

EPDM deck adhesive and contact adhesive quantities

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