Liquid polyeurethane

[geraldthehamster]

Which is easier and more cost effective for a DIY flat roof, with an OSB deck - EPDM or liquid polyurethane? I've successfully used EPDM, but not tried the liquid system.

Cheers
Richard

 

[Rufus Raintight]

Some questions

• How many square metres do you need to cover and what are you covering (garage, extension etc...)?
• Do you have any liquid polyurethane systems in mind?
• Are you going over the existing surface or putting new decking down?

 

[geraldthehamster]

Some questions

• How many square metres do you need to cover and what are you covering (garage, extension etc...)?
• Do you have any liquid polyurethane systems in mind?
• Are you going over the existing surface or putting new decking down?

Thanks for your reply. 25m2, garden building with warm roof, new deck.

No particular system in mind. I noticed Polyure in a builder's merchant's flier, then read about Elastathane. Atmospheric moisture-curing systems that you roll or brush onto the substrate, using reinforcing mesh to bridge gaps and joints.

 

[Elastomeric]

Which is easier and more cost effective for a DIY flat roof, with an OSB deck - EPDM or liquid polyurethane? I've successfully used EPDM, but not tried the liquid system.

Cheers
Richard

EPDM. Liquid systems require more than a half day training course to learn how to install them correctly. Especially fleece systems.

 

[geraldthehamster]

It doesn't look difficult

 

[Elastomeric]

It doesn't look difficult

It never does. I have some lads installing a 1000m of PMMA liquid at the moment, and at £150 a tin plus catalyst and quartz etc, if it gets ballsed up, it gets expensive.

 

[Rufus Raintight]

Liquid polyurethanes tend to come in two versions; a one pot wonder that overcoats or repairs the existing surface (These don't usually come with a guarantee) and then the full blown all singing all dancing versions that have either a fibreglass or a polyester reinforcement.

Upsides to polyurethane

• Moisture cured so no catalyst or additives to worry about like a GRP system
• Extremely flexible, so no problems with thermal expansion and contraction
• Sticks to everything (including contractors)
• Seamless finish (unlike EPDM)

Downsides to polyurethane

• Price - depending on the system they can get pretty expensive

If you have the budget and like a system then go for it, Liquid polyurethanes are really really good. If you want a seamless liquid applied system on a smaller budget then GRP Roofing might be the better option. It's a bit more fiddly to install but it'll still give you a seamless finish and a 25 square metre roof shouldn't have any flexibility issues which is polyurethane's main feature.

 

[^woody^]

I've spilt the like between the post, the name and the avatar.

 

[geraldthehamster]

Liquid polyurethanes tend to come in two versions; a one pot wonder that overcoats or repairs the existing surface (These don't usually come with a guarantee) and then the full blown all singing all dancing versions that have either a fibreglass or a polyester reinforcement.

It's the one-pot wonders I'm looking at, which claim to be suitable for a new deck as well as repairs to an existing surface. With reinforcing mesh to joins and gaps. I hadn't worked out the cost yet in terms of coverage (when I did a similar EPDM roof it came in about £18 per m2).

Not keen on fibreglass as I'd be against the clock and have visions of ending up with a pair of boots stuck in the middle of the roof.

At the end of the day there's no reason I can't use EPDM; just wanted to explore alternatives.

Cheers
Richard