How big should a roll of Tyvek membrane be please?

[happyhero]

Hi I am doing a DIY project shed and it has been recommended to me by a builder to use some Tyvek roofing membrane on my shed as it is a little different to an ordinary shed. I have clad the wall on the outside with ply and will now batten and then clad with featheredge, the Tyvek is to be put on top of the ply walls.

Anyway Tyvek was recommended as one of the better breathable membranes and someone is offering me a couple of started rolls. Not being a builder or roofer etc, I have no idea how big a 50m roll is when rolled up or where to find one to look at so can anyone tell me how many centimeters thick they are across the diameter when new so that I have some idea as to whether it is a nearly full or nearly empty roll I am looking at.

It is the 50m rolls that I am after and as I say they have had some used off them already.

I know its a funny question but I don't know how else I can be confident I am buying a roll with enough on it.

Any help appreciated.

 

[Mw Roofline]

They usually come in 1 or 1.5 mtr rolls and i'd say the diameter of the roll is about 8 to 10 inches? So imagine a giant toilet roll tube 1 metre long thats 8to 10" thick and that gives you some idea of how big a 50m roll is.

 

[RedHerring2]

Alternatively, pop down to the local BM or shed and measure one.

 

[SASroofer]

Or before buying the part roll, unroll it and measure it

 

[^woody^]

You can get 50m of non-Tyvek stuff for £35-£40 a roll, so unless you can get this part used roll for less than this, then you are better off buying new stuff

The membrane is so thin that unless you measure a tightly wrapped roll with a micrometer, then its very easy to use 15m and then re-roll the rest up a bit loose to pad the roll out

Tyvek is premium stuff and not worth paying extra for, for a shed