Quick Q for builders/tilers etc...

[Ja1983]

i`ve got a  :-# load of natural sandstone slabs (15mm thick) - ebay!

we have an ashphalt floor, i intend to lay them in the kitchen and the hall way as the carpet in the hall crawled out the other when i left the door open................ (honest darling !)

now i`ve been pestering B&Q, and the "now-it-all engineers" at work... but no-one will give me a straight answer....

B&Q said - special Asphalt tile adhesive, weighing in at £35 a bag (will need just over 2 bags)
to which i said - but this is cement based, and says "see manufacturers instructions" with regards to natural stone... now i`ve tried speaking to mother nature, she wasnt available....
The next line was use a levelling screed - which should key to the Asphalt, and then use a normal cheap adhesive... then i reminded them that it was stone, so the £8-50 a bag went to £16 a bag... and after i`d spent 2 days leveling/curing the screed (£15/bag) then laid the normal stuff, i`d still be at a similar price, but 2 days work down...

i also pointed out that as its cement based, could i not just use a mortar bed?

they said... "erm... i wouldnt like to say - speak to the builders yard"

the tiling guy sent me to the guy in the builders yard section, and he in turn he tried sending me to the tiling section, but i said nay! we agreed that in theory, the flexibility of a lime mortar should allow any deflection of the asphalt, and provide a good adhesion to the ashphalt, so long as it doesnt react... but if we were to seal it first, it shouldnt be ok. PVA (5 parts water to 1 PVA?) although, with Asphalt been an oil based article, will it key to the PVA?

the asphalt is OE layed thinly over a concrete (very rough concrete - thought of that option too!) which has been down for 50 years (this year) so shouldnt move much now..

also do i need to seal the stone underneath to prevent the tile drawing out too much moisture from the mortar - or do i just wet them off before laying ~ like in the old days of walling??

..and if i use a lime mortar bed, what shoul i use for grouting up the gaps? OPC mortar, grout? (will the grout kill the mortar or vice versa?)
I`ve got the masonry seal (£8.50 for a big tub, rather than the special tile sealant at £10 for a pop bottle) which i could try on the Asphalt...

also as theres enough stone to do the floors, the walls, the roof and my disco, we tried one using some left over grout for wood floors - it seemed to work, but hasnt dried too wel (after 48 hrs) i can only assume the stone has pulled too much moisture out of it thus retarding the curing process..

any ideas as i`m getting propper  :-# off with it all now!!

Cheers

Ja

[lee celtic]

Just did a search on google using stone to asphalt adhesive on two American sites they used neoprene modified hot asphalt (hot melt roofing tar) to stick the slabs down ,I guess it puts a damp proof layer down as well.

then brushed in bone dry sand and cement mix then a light sprinkle of water with a watering can so it wets the stone and lets the sand and cement set slowly with no mortar streaks on the face of the stone .

This was used inside and outside over a tarmac drive.

makes sense but I'd still look into it with a professional , Maybe phone a tile warehouse.

[v8kenny]

Can you not just lift the asphalt if it's only a thin layer and then lay the stone on a mortar bed ?
Use PVA in the mortar, that'll get the [!Expletive Deleted!] stuck down !

[MudRat]

lay floor tiles on a wet bed of screed, they will level up and stick at the same time, if you are worried about adhesion, then test a slab first.

[v8kenny]

that'll get the [!Expletive Deleted!] stuck down !

Wow, I never thought THAT word was a sweary word !.....................................................................................sorry !  :oops:

[Ja1983]

i have had more differant advice from everyone i ask!

removing the ashphalt is not an option - due to the age it could well be an ACM (Asbestos) and also the concrete below is VERY irregular (open door, kick it round, let it set and level with black stuff) as it is exposed under the stairs, where me and "von klobber" (big hammer) made a new storage cupboard!

curious about the american method, but i can see it getting messy (downstairs already decorated - inc solid pine fitted kitchen!)

from what i`ve learnt so far it looks like i`m going to scrub down the ashphalt, PVA to seal it, then stone adhesive to bed them, with a masonry seal applied 24hrs after, grout up with normal floor tile grout before a final application of masonry seal...........

sound good?