Which EPDM system is the most cost effective and best?

A client, who was looking to replace his old flat roof, asked me what system would I use on my own roof and why.

I immediately replied HERTALAN or PRO-EPDM

He responded by asking why would you choose these systems as their BBA length is less than other cheaper brands. Meaning Firestone and ClassicBond.

It got me thinking about the BBA certificates and what they actually mean for the systems, after-all the BBA certificates are on the full system not just the EPDM. So if you use adhesives and accessories that aren't listed on the BBA certificate you may as well tear it up.

The BBA certificates for all systems are very precise in how the products should be fitted to achieve the service life.

They give accurate details on the following key areas

• How to install the EPDM membrane.
• Which adhesives to use and how much.
• Which accessories are included in the system.
• Who should install the system.

All systems require training from the manufacturer. If you don't have training and want to know how to install the systems yourself then videos and instruction are easy to find on the internet. Also all manufactures offer training days.

After this the systems vary massively.
Some manufacturers will supply their systems with
• Cheaper adhesives.
• Accessories that are non BBA approved.
• HERTALAN and PRO-EPDM don't have any cheaper non BBA options.

Here are my costings based on the original 5m x 6m enquiry and if you want to read more on how I get these figures I explain all the BBA documents further on in this post.

This table shows the Non BBA certified options and the prices. (ex vat)

nobba.jpg

So remember non of the above systems comply with the BBA testing standards and therefore  wouldn't be guaranteed to last the length quoted by the manufacturer in their BBA and would highly likely start giving problems within 10 years. The Hertalan 1.0mm has the best chance as its the same EPDM as the Hertalan 1.2mm and has the same adhesive.  However the other 2 systems just aren't going to last that long due to being installed to an uncertified method.  If suppliers tell you that you need less than is suggested within the manufacturers BBA certificate, then the system will ultimately fail. If it would work with less adhesives it would have been put through the tests with less adhesive.

In the table below we have all the options that are covered by the BBA certificate.

bba.jpg


Following on from my pricing I explain below how I reached these conclusions and how to interpret the BBA certificates and what quantities of adhesives are actually required by the manufacturers.

Firestone RubberCover EPDM
One of the cheapest systems on the market for EPDM is Firestone RubberCover. If fitted correctly the product comes with BBA certification for 30 years on roofs up to 150m2 for domestic applications. Anything over 150m2 there is no BBA certification. The perceived low cost of this system stems from stockists/retailers selling the incorrect amounts of adhesives to make these systems appear cheap. To give an example of this, take the 10 litres of water based bonding adhesive, most online retailers suggest it will cover 50 sq.m however to comply with the BBA you need to use 1.3 litres per m2 (0.8 litres on the deck and 0.5 litres on the EPDM) which is a massive difference to the advertised 0.2 litres. Similarly if you just put it onto the deck and push the EPDM into it you need between 1.47 litres to 2.45 litres, depending on the condition of the surface, so even more expensive. So the correct amount of adhesive required, based on the manufacturers figures and to comply with their BBA certificate, will cost you between £9.75 + vat (for the 1.3 litre option) or £18.40 + vat (for the 2.45 litre option). So maybe this system isn't as cheap as has been suggested.

ClassicBond EPDM
Then we have ClassicBond which is a very similar system to Firestone RubberCover.  On the face of things a 35 year BBA. But again everyone sells the ClassicBond with a water based adhesive that hasn't been through the rigorous BBA product testing.
So if you want to comply with their BBA then you need to use contact adhesive and you need to mechanically fix the sheet around all perimeters and around any openings (skylights access hatches etc) with their RUSS strip. (This is a reinforced piece of EPDM with a pre attached splice tape that is screwed down and then you splice the back of the main sheet to the tape) So by the time you have added on the Russ strip and the mechanical fixings plus the contact adhesive you end up a long way from the price quoted by some retailers with little or no flat roof experience. (ClassicBond is also sold under the name Carlisle Syntec)

Duoply EPDM
DuoPly is a Fleece backed version of ClassicBond and again on the internet is advertised with a water based adhesive (WBA) which isn't BBA certified. You have to use a polyurethane (PU) adhesive and the RUSS strip system at perimeters and skylights etc. (This is also sold under RubberBond)

HERTALAN and PRO-EPDM
HERTALAN and PRO-EPDM systems have a 25 year BBA and don't have any cheaper options for installation. So prices that are advertised on the internet are as they should be. This is where these systems start to prove how cost effective they are and look better than originally thought.

RESITRIX SKW & SR
RESITRIX SKW and SR both carry a 30 year BBA and the amount of primer that is advertised (250g per m2 when applied with a roller or 120g per m2 if applied with spray canister) is as per manufacturers guidelines and that which went through the BBA testing.

So now I have explained the most popular EPDM systems and what must be done to comply with their BBA certificates and the costings on my clients original enquiry which was his 5m x 6m double garage roof, you can clearly see to achieve a roof to a BBA certified standard its very different to what is advertised by many of the stockists and dealers and you can see why I immediately said HERTALAN or PRO-EPDM as my preferred systems.

When it comes to installation HERTALAN and PRO-EPDM are uncomplicated systems that make them fast and easy to install and therefore even more cost effective due to lower labour costs? So in terms of productivity and material costs to get a BBA certified roofing system HERTALAN EPDM and PRO-EPDM are certainly in my opinion the best option.

For anyone who is interested in seeing the BBA certificates I have included a link below.

All prices are from internet retailers and details are available on request.

References

BBA – HERTALAN and PRO-EPDM 
BBA – RESITRIX SKW
BBA – RESITRIX SR
BBA – ClassicBond 
BBA – DuoPly
BBA – Firestone