# UK Roof Measuring Units - Metric vs. Imperial systems

Hello fellow roofers!

I'm a roofer in US, and i'm working on adding metric system to our roof calculator app. I did some research already, but I need to get some exact info, to do this properly.

All questions below assume installation of Asphalt / Bitumen shingles.

So here is what I'm looking for:

1) What is your pricing UNIT - 1 m^2 or 10m^2 (In US we use "squares" which is 100 f^2 or 10x10ft area)
Example - when you price a job - which is say 150m^2 - do you calculate it price/m * number of meters or how?

2) In which quantities do you buy shingles? - I see on some roofing supplier websites (roofing super store for example) price per "bundle" or pack of shingles which is I believe 3 m^2

In US, contractors buy materials in squares (which is typically 3 packs).

3) Plywood / OSB - what is the typical size and thickness? I found 1.2m x 2.4m AND 1.22m x 2.44m - so which one is more common?

Also what is the minimum thickness used in roofing and typical thicknesses?

In US it's "1/2" inch and 5/8 inch

4) Ventilation - namely Ridge / Soffit vents. In US we typically use a 20 feet roll of something like Cobra vent ( http://www.gaf.com/roofing/residential/ ... -Vent.aspx )

What do you use in UK? please provide name or type and dimensions

5) Trim - I found that typical drip edge trim is 3m long (equivalent of US 10 ft) - is this correct? Do you use it only on eaves or all along roof perimeter? What is a typical price for a 3m drip edge trim?

6) Roof Pitch / Slope: I assume from the info I found, that you use degrees. But I've also seen ratios. How do you measure roof slope (industry "standard")?

7) Ice and water shield / barrier: (example: http://www.homedepot.com/buy/building-m ... 71695.html )

This is a peel & stick bitumen based membrane, applied in valleys, along eaves, and around skylights.

Do you have an equivalent in UK (except for torch-applied, as now one uses torch in US any more). What is the name, and physical size of a typical roll - I assume 1*20m

I might have some more questions down the road, but this is what I need to get started.

Thank you very much for any help, Leo
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