indoor 'paint on' floor sealant - to form damp proof membrane

[what..the?]

the house has old concrete floors and no membrane. To dig up the floor to put one down would be too costly and time consuming. I hear the paint on forms are very good. There's is a product called G4 damp sealant which will cost me £400 to cover the 90 m2 in the recommended 3 coats. But now I have seen that wicks do a similar product possibly a lot cheaper so would like peoples views and hear experiences of anyone has used these products

http://www.wickes.co.uk/invt/241218

http://www.mbfg.co.uk/sealers/1198.html

Thanks in advance

[buildersmate]

Have you considered this more conventional DPM? Paints are only as good as the application; a polythene sheet of 1000 or 1200 thickness truly is a barrier to damp and is what is normally used. Clearly one has to lap it up around the edges and cover it over, but it is going to be cheaper than the material cost and labour of paint application. Depends what's going over it, I guess.

http://www.screwfix.c...1000ga%204m%20x%2015m

[what..the?]

i've got tiles going over it. I was recommended the paint on version I think because we couldn't dig down I think they had a issue putting a DPM on a much higher floor surface level? But if they are putting the paint on version I don't see a problem with the similar DPM. Only issue I would have with a DPM is that the whole ground floor needs to be done 90m2 and there are a lot of fiddly bits to cut the dpm to fit, I worry lack of attention to detail my cause me problems.

[buildersmate]

Well certainly polythene DPM have to have some sort of covering prior to the final finish layer, so this implies your builders are not planning to put any insulation down - one wonders how they are meeting thermal regs for Building Regs. The conventional way to do this on old surfaces that had no DPM from the start is to dig down a bit.
Let's see what The Builder / Albags have to say on the matter.

[what..the?]

We can't dig down due to the time (3 weeks) and cost (5k) implication. So this was why we are looking for options to put on top of the existing floor. I just asked about membrane and the builder said it would depend on which type of membrane I wanted but that plus a final finish layer would raise the floor and cause us problems with the doors etc

[jackthehat]

what...the? - Your inconvenience with regards to time/cost, etc. shouldn't mean that you can skirt round the Regs, I'm afraid.

If the Building Control Officer is not happy with the floor construction, he can insist that your builder constructs a floor that *will* conform to the Regs.
You will have then wasted both time and money on this quick/cheap solution.
I'm afraid shortcuts in these situations rarely are just that.

[AlBags]

You should use .. and tank it with Thoroseal.
http://www.thoroprodu...cts_waterproofing.htm

[The Builder]

Hi Mrs What. Re: Building Regs. I guess what the others aren't aware of, is that yours is a renovation ...... not a new build. As such, they can't insist on the latest regs, provided you're not making the overall insulation level worse than it was. As you're having a new roof structure, windows etc, then there'll be plenty of new insulation involved. That tiled floor is going to be mighty cold though :o(

The products you link to ........... one is Bitumen based.......... not ideal for direct tiling, but possible. It used to be used a lot, but with a sand & cement screed laid on top........ then tile on the screed. Used properly, it provides a good, durable barrier.
The other one is just a brush-on waterproofer. I don't think it would provide a proper barrier.

The best kind of paint-on products are similar to Al's suggestion. Cementitious, they're called :o)))
I've used "Vandex" in the past. A similar, very effective product.
Also, years ago I remember using a 2-part poyester based one called "Polybond" if I remember correctly. I think it was "Polybond Q19". I'll check that for you. Superb product similar to polyester resin (used in fibreglass cars bodies etc). 2-pack with a hardner.

Since you're going to be tiling. I'd do what Al suggests, and go with a cementitious.

I have to agree with Jack and BM about the insulation though, for your comfort level. Is there any reason why you can't lay insulation over a membrane, on top of the existing floor .............. then chipboard and tiles?

[what..the?]

won't adding insulation increase the height of my floors substantially?

The second one I have suggested is polyurethane that is painted on and hardens is that not good then? Three layers are applied and the last coat is sprinkled with builders sand as it dries to create a surface for the tile adhesive to grip.

[macworm]

I would consider putting down wood block rather than tiles, these can be bedded in bitumen based compound, look good and provide insulation. I have pitch-pine blocks(9" x 3') reclaimed from an old church but hardwood may be better as they are easier when sand out slight imperfections.

[what..the?]

I wouldn't be too keen on wood because of the potential damp issue if the DPM seal is not brill and I also have house rabbits which is why the ground floor is tiled...anything else they would eat. I will have very large rugs which will help keep it warm underfoot these can be washed easily and if eaten by the rabbits badly, replaced.

[The Builder]

Something very strange going on with the links, Mrs What. I've clicked on your second link again and got a different product ???
Yes, that MB Fibreglass one looks good. Very suitable as an alternative to the cementitious ones I mentioned earlier. Tiles on top of that would be fine.

Do you have low ceiling heights?

[what..the?]

No I don't have low ceiling lights but an increase in the height of the floor would effect a lot of things like patio doors fireplace, steps, all sorts.

I have however been considering some kind of secondary heating under the tiles so they are not too cold ...which to be frank I don't know if the cold floor will bother me.

Issues

-cost to buy - £2k based on 80m2
-cost to run - currently unknown
-I have no insulation in the floor to keep the heat just going upwards into the house than downwards into the concrete and bedrock below and therefore that's lost heat, so not as efficient as it could bed, and I can't add insulation now.
-The fact I am tight as a ducks arse and likely won't want to put it on to save money = no point in having it.
-I already have a wood burner and central heating in these rooms anyway, and will put rugs down
-If it breaks/system fails I'm stuffed as can't dig up all the tiles.
-However if I don't put the system in will I regret it?

Any thoughts?

[macworm]

I assume you are thinking of electric u/floor heating in which case without insulation it will cost a bomb to run and isn't guaranteed to out last the tiles. If ceiling height is not a problem I would think about insulating the whole floor with a 25 - 50mm layer of Kingspan or polystyrene and covering this with 22mm ply fixed through the insulation to the old floor, then you can tile over and have the benefit of the insulation. You could lay a DPM under the insulation first. Just remember that this will also lower the height of the door openings.