bitumen floor

[figgd]

I have a red tiled floor over which are laid carpet tiles. The carpet tiles have a strong rubberised base. The old red tiles are laid on mortar which is on roman concrete and hardcore. There is no DPM but the floor has been sealed with Synthaproof. The bottom of the carpet tiles suffer from condensation and mould especially in winter probabley caused by a cold floor next to the warm carpet.
I have seen a new building with a top layer of bitumen instead of a dpm and wonder if this would solve my problem. I could replace the 1" tiles with a poured bitumen floor. Has any one tried this and are there companies that do this work?
Thanks for any advice

 

[masona]

There is no DPM but the floor has been sealed with Synthaproof.

What room is this floor ? Not sure when you say 1" tiles. If I said to you, can you raise the flooring another say approx' 50 mm, is it possible ?

 

[figgd]

The room is a lounge in a late Victorian house. Surprizingly the other rooms in the building are timber and the house has one of the good first DPC's which I believe were themselves "bitumen poured".
No the floor could not be raised above the adjoining rooms.
The tiles are approx 6 inch square and 1 inch deep.

 

[masona]

I'm still trying to understand what floor finish you want. The difference between bitumen & synthaproof is that bitumen need to be heated to 150 C for it to pour where synthaproof is a cold pour basically doing the same job. You cannot not have a bitumen floor finish unless you want floor tiles on top.

 

[figgd]

Quote "I could replace the 1" tiles with a poured bitumen floor."
Sorry, I understand the problem now. I envisage taking the tiles up and replacing them with bitumen. Then when it is hard, perhaps line it with building paper and replace the carpet tiles. Thats the aim though I cant see any mention of this process elsewhere. Am I being over ambitious? I have seen a bitumen floor done like this many years ago and it is as good today.

 

[masona]

Okay, I understand now.

Bitumen is a better material but the only problem I can see is that the bitumen have a softening point range between 70 to 95 degree. When the room reached the temperature, it will feel like walking on sand unless a very thin layer. If you want to use bitumen, then the one to go for is probably 95/25 pen grade as they do this on flat roofing. (95 is the top temperature before softening and 25 pen is short for penetrating which for hardness), not sure if you want to do this yourself but it's easier and just as good to use a few coats of Synthaproof (Synthaprufe is the correct word !) which is a bitumen base thinned down.

See this , maybe cheaper to buy it in 45 gallon drum depending how much you want.

 

[figgd]

Thanks. Thats great information.
The present tiles were syntheprufed about 4 years ago and they are well sealed. But it doesnt prevent the cold causing the condensation below the carpet tile. Thats why the idea of bitumen is being considered. It should give a waterproof seal and hopefully a degree of heat insulation.
I know what you mean about the sandy feel in warm weather. A science lab in our local school had a 1/2 inch bitumen floor and it had a pleasant bounce. I doubt this will be my problem. The floor will be in a cool room with a these thick carpet tiles on top. The other floor I had seen was just polished with matting in various places and looked and lasted well.
I doubt I'll do the bitumen part myself so I guess the next step would be to contact a reputable flat roof specialist to see what prices look like.
Thanks again for the info

 

[masona]

I guess the next step would be to contact a reputable flat roof specialist to see what prices look like.
Thanks again for the info

The problem is, they most likely won't know the difference type of bitumen. See this and ask the question in the comment box, they may tell what suitable products and your nearest stockist is. I work in the bitumen lab testing but can't tell you what grade is suitable for you !

 

[oilman]

The cold is not the cause of the condensation below the carpet tiles. The Synthaproof has not sealed the tiles, (and a good job too). The floors as originally laid would have had airfolw over them to take away the moisture. This was easy as the heating was done mostly by open fires which cause huge draughts. Modern living cannot cope with the real world, and so we finish up with houses which don't have enough air flow. The way to get over your problem is to put a raffia or sizal or similar mat on the tiles, then the moisture can escape. Provided there is airflow, your floor is safe. If you try to just stop the ground moisture at the top surface of the tiles, you will have bigger problems later to deal with.