by insulationgrants »
Thu Apr 23, 2009 3:43 am
I spent the best part of my earlier career in roofing approx 13 years and I have used practically every type of product there is so here totally impartial advice as no longer am in the roofing industry.
Pros & Cons of each type of roofing system I can think off.
Heat wieldable PVC, preferably a homogenous sheet minimum 1.2mm.
On my opinion the best type of product on the market and heavily used in commercial work.
Recommendation would be Sarna or Protan.
Weakness: PVC will need additional protection from foot traffic. Ideal for low foot trafficked roofs.
Felt roofs: If you get a dual reinforced polyester cap sheet and a decent contractor you will have a great roof however felt comes in a variety of qualities and prices and cheap generally means do not use.
Recommendation would be Icopal, the Andersons brand, Techno Torch is a great economy product and their higher end product Profiles is great to work with. IKO also has some good high end products. Erisco Bauder is very expensive but the quality is exceptional.
Asphalt: Great for car parks however it can crack with frost, is very heavy and need a solid deck ideally concrete and screed and can suffer from slumping and blisters in hot sun.
Recommendation do not use for domestic use and I would not recommend above anything with high humidity such as a commercial kitchen or swimming pool.
Rubber sheets such as Goodyear.
In theory it sounds great with no joints however its puncture resistance is very poor as it is unreinforced, it tends to shrink and if you do need laps then it is a disaster waiting to happen as the solvent laps are practically impossible to seal if it is below 5 degrees. An added problem is the laps vulcanize and this makes repairs more difficult than they should be.
Personally I would only be happy using rubber on water reservoirs as one sheet and covered over with soil as it will not pollute the water and also as a gas membrane again protect with soil. Personal preference would be Dunstable Rubber.
Coating systems, GRP, Polyurethanes, Spray Foams etc.
Forget it under 5 degrees and forget it if they are not reinforced.
Some of the reinforced polyurethanes are good for box gutter repairs as some stay tacky and also good for roofs with details that would be impractical to seal either due to limited access or a potential for a fire hazard such as a chemical store.
If you have clear blue skies and a nice summer’s day then this will work but unless you have perfect conditions I would not recommend either type of product as it has a habit of peeling off.
Recommendations none.
TPO roofs, basically like a PVC , but is more environmentally friendly.
I am not a fan of TPO as it is difficult to weld and has poorer fire properties. If you must use one use Sarna.
Green roofs basically a garden roof.
Very expensive, environmentally excellent and Erisco Bauder would be my recommendation.
Self adhesive felts.
The theory is you do not need a gas torch which is fine right up until the point you have to dry off some rain. You really need a new plywood deck and the weather to be sunny and above 5 degrees preferably much warmer.
Not a fan of this product as it can be rather soft to work with, of poor quality and the minerals fall off a lot more than other felt. However if your a DIY hand it could work in the right hands.
My tip is to try bonding the underlay straight to the plywood upstands without primer as in my experience it sticks better, however you could try both options and run with the one your happy with as moisture and weather will play a big part in how successful his will be.
Keep your upstand heights low as it will need mechanically fixed as the bitumen is so soft it will slump, the minimum height should be 150mm at walls.
The above is backed up with experience and what you will find in some of the BBA certificates and Building Research establishment guidelines and NFRC guidelines.
Regards
Jim Barrie
Former Estimator & Roofing Technical Advisor
Now a Government insulation grant advisor
