Waterproofing, membranes or tiles?

Hi all

I made a search for some contractors in order to get a quote for waterproofing a flat roof.
They gave me a quote of installing bitumen rolls on the roof. They said that it is impossible to locate from where my leak is caused and they also said that my approach with a portland cement - epoxic resing mix was not a good solution for waterproofing.
Apparently all three gave me a quote of bitument rolls and I have a few issues with that. One is that these rolls seem to be quite a cheap nasty thing (apparently bitumens cause cancer). They also cost about 4euro per m2 whilst the quotes are between 13-15euro per m2 meaning that the contractor will make a 5000euro profit for about 6 days of work
So I was thinking of finding a different approach. Do you think that installing tiles on the roof is a good idea for waterproofing? Or will the roof look like a giant shower?

 

I agree that Portland cement isn't good for waterproofing & I wouldn't use tiles either. I don't agree that it's impossible to find the leak. If you can get a pressure washer or maybe even a hose, on the roof, you have a chance to find the leak.

Also, your calculation of his profit doesn't take into account labor help cost & other costs.

 

Ya, there is a lot more involved than just material costs before any company turns a profit. Besides the actual money paid out for labor, there are any taxes and insurance that is associated with the labor cost. Someone pays for the workers and material to get to the job. Then there is the companies overhead; tools, trucks, advertising, etc. There may be disposal costs also.

While I can understand the cancer risk for those working with the material, I wouldn't think there would be much of risk for the end user once it has been applied. Since 3 separate companies all recommend the same fix - I would think that would be the way to go.

 

Ok so...
3 companies gave me quotes. One of them I dont know where they found me whilst the company that I actually called knows how they found me so I think that there is something fishy going on with those.
The second company proposed the same solution with bitumen rolls but I dont know the brand or the type of the product.
The third company is talking about this product:

http://www.vallizabban.com/en/schede...astogum_PL.pdf

Which is a modified bitumen roll (SBS membranes). That composition (SBS) is stated in a similar product in the US that it contains substances known that they cause cancer. Also it is stated that bitumens in general cause cancer.
Another issue is that this product is sold by the same company that gave me the quote for euro 3.95 per m2. Their quote for application if euro 13 per m2 and that involves:
Applying bitumen on the surface of the roof to make the bitumen rolls stick.
Applying the bitumen rolls.
They will not fix anything else or do any maintenance to anything or prepare the surface at all. They will just stick them to the roof.
Their engineers also said that it is impossible to find the leak. I tried to find the leak my self with a hose but with no luck. The roof sometimes leaks when it rains sometimes it doesnt.
My calculation is probably wrong on how much profit they are making but I dont think that this is actually the best product or solution I could go for but its probably the most "suitable" product for them to make profit. The fact that they never actually said that this will fix my problem makes it even more wrong for me to consider that option.
This was also the previous waterproofing method that I had and when those membranes eventually got unstuck they collected quite alot of water underneath that damaged damaged most of the ceilings in the appartment so I am a bit worried about it.
It is also stated that once applied the surface will no longer be "walkable".

What do you think of this product? Have you ever heard of it?

Do you know of any product that I could alternatively apply that is not causing cancer, will leave the surface walkable and wont require a thermal application? Like a super resin that I could just roll on the roof?

Many thanks

 

Let me see if I understand everything so far. 3 companies said that they can't find the leak but they can install a new roof with no guarantees. Is that correct?

If I had to open the ceiling from the inside to find the leak, I would do it before I spend thousands.

 

What I use in Florida is a torch applied modified bitumen about $125 sq for materials and charge $300 to $500 sq. You should remove old roofing to replace any rotten decking. Going over top is a bad idea although most codes allow. In Florida we install a fiberglass base sheet over plywood then cut 9 inch strips off the roll and install them upside don around the perimeter, then install the drip edge and torch the rubber over that. As far as charging too much, Roofers pay the highest comp rate in the country and insurance aint cheap either.

 

Yes, none of the three companies said that they can find the leak but they said that they could apply new bitumen rolls on the roof. One company gives a guarantee but I dont think its for the leaks, its probably for the condition of the bitumen rolls. They also said that this guarantee is more of a friendly agreement and they are not really obligated to honour it.
As the situation is at the moment I think I might try to find the leak first and then think this all over...

 

Exactly my thoughts. Look for the leak.

 

I can't imagine a roofing company not guaranteeing their work not to leak