a moron's question: Do we really need a screed?

Screeds, what are they for? They provide: A nice and flat surface Impermeable (not that much) hard-wearing So? There are boards used for UFH (and similar products) which offer just t= hat...only, they are 10mm thick. Having removed the screed from a partially screeded bathroom I'm just wonde= ring if it would be better to use the limited height available for insulati= on rather than a screed - let's say, I'd lay a 50mm slab of Jablite or simi= lar on top of the concrete slab, then an hard wearing 10mm boards to accomm= odate the UFH and then I'm left with about 12mm for the tiles. The lot woul= d cover the available thickess of 70mm. Any problem?

Reply to
swimmydeepo
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  • a stiff, non-flexible, surface

If you're starting with a concrete slab, I think that should be OK. (An expert will be along shortly to explain why that is wrong)

Can't see any.

Reply to
Martin Bonner

On Thursday, October 25, 2012 11:54:24 AM UTC+1, snipped-for-privacy@yahoo.co.uk wrote= :

that...only, they are 10mm thick.

dering if it would be better to use the limited height available for insula= tion rather than a screed - let's say, I'd lay a 50mm slab of Jablite or si= milar on top of the concrete slab, then an hard wearing 10mm boards to acco= mmodate the UFH and then I'm left with about 12mm for the tiles. The lot wo= uld cover the available thickess of 70mm.

If the surface is rough, you've got concentrated point loads, resulting in = the insulation sinking much more easily. I don't know if its worth putting = a little self levelling down first just to stop that

NT

Reply to
meow2222

You can tile over wood, provided it is securely fastened down, EG, plywood screwed over floorboards in an upstairs bathroom, that is to say, you can't just tile over the floorboards because they move individually, hence the plywood sheet. Your proposed floor will essentially be floating, and if it's tiled, it will crack up in no time

Reply to
Phil L

I don't get this...you are talking of floorboards while my floor is basical= ly a concrete slab (at this stage) laid on top of some hardcore over ground= (so more stable than a suspended floor).

Just as I'm getting more info about screeding...I'm puzzled by the many var= iants available; more strikingly, some recommend a watery kind of mix while= others opt for a near dry mixture?! Can anyone shed some light on this con= trasting views? Were those comments addressing leveling compound v proper s= creed without realizing the difference? Then, there is another question related to the thickness needed for electri= c heating cables (7mm thick) - some recommend a fairly thick screed (at lea= st 65mm) to be laid on top of the cables while others say that the screed s= hould be thin (25mm above cables so 35mm should do nice) so that the heatin= g time is shortened - to me the latter seems the obvious choice (and quite = handy too as there is no much height available).

Reply to
swimmydeepo

But you are talking about laying tiles on 10mm boards over jablite, and I said they won't last five minutes.

I think you're getting bogged down in nonsense.

Screed is a top coat of concrete or mortar or any other hard setting substance used for flooring, it can be liquid, dry or anywhere inbetween, it's not relevant what consistency or method is used in laying, only the finish

it's entirely up to you, if you're putting UFH cables in and want to screed over them, then feel free, but different people have different ideas and a thicker screed over the top will take longer to heat up, but a thinner one isn't very strong and may crack with the heat.

If you've got 70mm to play with and bearing in mind you want 15 of those for the tiles, you'll have to decide how much (if any) insulation you want under there.

If your house is less than 25 years old the floor's already insulated, if it's not you'll need at least 25mm of jablite which will give you 30mm of screed then tiles over this.

And your original question as to 'what is screed for?' it's so that the floor can be poured in one, usually while the building is only at DPC level, without paying too much attention to detail, then when the rest of the building work is completed, the screed is laid

Reply to
Phil L

I don't know the difference between the Jablite boards and these:

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that sort of boards (there are many similar in the market) might repres= ent just what I needed...at least from the way the product is described - i= n fact it would make it much easier as I can just laid them on top of the c= oncrete slab, fix the heating cable on top and then tile over (in the origi= nal idea I would had to use a slab of Jablite and then a 10mm board + UFH c= ables and tiles on top).

How about that?

Reply to
swimmydeepo

esent just what I needed...at least from the way the product is described -= in fact it would make it much easier as I can just laid them on top of the= concrete slab, fix the heating cable on top and then tile over (in the ori= ginal idea I would had to use a slab of Jablite and then a 10mm board + UFH= cables and tiles on top).

Well...another link to reinforce my point:

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The final part of the second paragraph (FAQ 2) states that: "The 50mm boards are very popular in new conservatories & extensions where = they effectively replace the top screed."

Indeed, who need a bxxxxy screed then?

Reply to
swimmydeepo

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