Suggestions for Liquid Flat roof product in Canada

Hi all, I have a 7200 sq foot flat roof in Canada, maritime climate. Tried GACO silicone on another roof, liked the product, bank didn’t because oddly enough GACO couldn’t or wouldnt show it had a long history in cold weather climates. My area is also very small, very conservative, and resistant to change, so liquid systems aren’t really known here it seems.

Substrate is mostly weathered SBS and a section of new SBS that leaked.

Anybody have any suggestions for a quality paint-on or roll on product, maybe fleece reinforced, that has a good lifespan and has been around and used in northern climates? One that doesn’t need excessive substrate prep other than cleaning and vacuuming.

I’m looking at a couple other liquid cold applied systems, one is Soprema Alsan 230 Winter Field and Flash. Other systems require putting down a glass coated foam level and then a cement board (not happening).

Thanks a ton everyone, kind of stuck right now with winter coming.

Get a list from the bank of what they will accept. Start from there…

Check. They don’t care so long as it isn’t rubber and has been around a while in northern climates. They had a point, rubber isn’t SBS.

I would look into someone that is confident in Hydro-Stop.

As in they actually mention the product themselves without you bringing it up.

It is a paint meshed with fabric.

Paint- fabric-paint.
Re-paint all with the base coat.( blueish grey)

Then paint with the top coat twice.(white)

Consider an asphalt coating to get you through the winter. You MUST vapor vent the leaking area, or you’ll have nothing but trouble.

how would one vapor vent a flat SBS section?

Thanks! Just watched a video, very promising.

The object is the trapped moisture in the system. water to ice expansion is 10% - water to vapor is 1700.

Thanks Darkthirty, I did not know that statistic, learning roofing has been a really interesting process actually. You’re say the volume expansion of water trapped between two layers would be only 10 % more size when the water freezes in winter but 1700 when it changes to hot summer and the asphalt roof heats the water to vapor?

If so that would explain the surprisingly large puffy bubbles in a couple spots of the weathered SBS.

Moisture pressure will divorce coatings and repairs

I’ve looked at those systems, but could never get the numbers to work. The labor and material, not to mention the logistics, were too far out to make viable. I’ve got a graco 4030 roof rig to spray the layers, but you also have to back roll and play with the scrim rolls. 72SQ is a lot of roof to get covered. I could coat that at 1.5 GPS in an hour and a half.

What systems are you referring to? Thanks for all yr replies so far.

Slobber coating, embed scrim, slobber coating… The warranty specs are no different than a single ply.

What system is the,fast one then you use instead? SBS with torch apply?

I install a lot of EPDM. Not sure that Mod Bit is faster, I repair it, but won’t bid it.

How hard is EPDM to install?

I self-taught myself SBS torch on to do the section I started this thread with talking about how it leaked and now I have water between the first layer and the new torched on section where there are ponding sections. As a DIY guy I was following the roofing manucturers advice to use a heat gun to weld the SBS rather than learn how to torch - totally stupid advice to try and use a heat gun on 1200 feet of seams at 3 minutes per foot - the sections are mechanically fastened with a 3’ strip to heat weld to seal. After 3-4 sections of heat gun I tried torching and that was far faster and more reliably done but unfortunately we had heavy rain and the first 3-4 sections were in a ponding area and they let water under the whole thing.

So. Removal is a major major problem, don’t want to do that.

New plan is to cut open each section end to end in the middle, use the torch to dry it out underneath, then use Alsan flashing to seal the slits to make watertight and remove the moisture. Then install two roof drains in the worst ponding areas - there is a 2’ void space underneath and the whole top floor is being gutted and renovated so several areas are already open underneath the deck. Then once drains are in and the leaking section has been hopefully properly dried and sealed … go over the whole roof with a liquid membrane to make a seamless membrane.

Which brings us back to my starting question which liquid product. Hadn’t considered EPDM can only say I’m an unskilled person and doing careful prep plus rollinq slobber coats as you call them is just the right level of difficulty. Really I just want to learn a reliable low skill no torch economical system.

I’d be happy to pay for your time to look at some videos I’ve shot of the roof and get your feedback as a pro roofer on my plan via phone or video. If you’re interested.


Only way I’ve done APP MB is to torch the whole roll, thought SBS was for hot mop, just doing seams works? I don’t do MB roofs, just repair them. If there is moisture in the system the insulation and deck will degrade. Might as well do the Alsan thing on the whole roof, if it will work.

Thks … I was leaning that way until I got the cost of the Alsan liquid products and it is 500 $ per 5 gall buckets with coverage of 90 sq ft only … thats 40K just for the product and not anything else, no flashing or fabric or primer. If I owned a 20 story bldg downtown Manhattan that couldnt be re-roofed and had to be recovered those prices might seem reasonable but for a easy access 2 story wood frame in a small town thats just crazy.

… the manufacturer of the SBS sections we put down had come out with a version where you just sealed the 3 inch strips outside the fasteners… they were suggesting using just a heat gun so thought it might work … we tried it and results as above.

So now we’re just trying to remove the moisture, seal the cut open sections and then go over it all with a liquid membrane … but which one?

How deep are the ponds? Is this roof 72 SQ?