substrate question

[Spud]

got a 45 sqm floor to lay on a 25mm modified sand and cement bed with chicken wire mesh reinforcing, 900x450 porcelain drop lay method ,subtrate is a fibre screed 40mm thick over ufh, the substrate is showing cracking which i was going to repair with the epoxy resin and steel pins repair method, the floor is on block and beam construction over a basement with insulation then ufh then the screed but it is showing signs of movement ,as it is unbonded do i decoulple the floor using a cleavage membrane or do i bond it to the substrate in hope it will tie the floor togethr with the slurry and chicken wire and give it the required 60mm over the ufh ? any advice appreciated

 

[jay]

hi i would be more likley to decouple that way you are covering all futre probs :8:

 

[White Room]

I'm with jay on that one, a decoupling membrane to keep it seperate from substrate.

I would have thought the fibre screed would have been 60mm at least

 

[Colour Republic]

the floor is on block and beam construction

I'm really not keen on this type of construction, I don't know why considering that a lot of continental buildings use this method and they tile floors a hell of a lot more than us. I just think there is too much room for movement. Laterally. So a cleavage membrane would be essential IMO

 

[Spud]

I'm with jay on that one, a decoupling membrane to keep it seperate from substrate.

I would have thought the fibre screed would have been 60mm at least

unfortunately its not, there was 4 tons of building materials stored on the screed which has assisted in creating the cracks, now you can feel the movement when walking across the floor so i am in 2 minds whether to tile it or not ,repairing the cracks will strengthen the floor a bit but will it be enough to take the weight of the new flooring ?

 

[White Room]

Thats an excesive amount of weight on a block and beam, would the insulation have been pressed down with the weight of materials over a time.

I feel I would back off, I can't give a definitive answer to the problem though

 

[Colour Republic]

Actually this thread could answer a question that has been going round my head for some time...

Do buildings expand and contract at the same rate between 0-20 degrees as 20-40 degrees and how much does humidity (water content) play a part in this?

Specifically concrete structures (but timber and brick construction would be handy to know)

So for example, if you draw a graph would it be a straight line or a curve?

This might explain to me why certain methods work on the continent and not in the UK.

I might have to wait for the human wikipedia that is Ajax to give me a full explanation on this one!

 

[Rob Z]

Hi Gary, I don't know all of the terminology that you and the rest of the guys have used in this thread, but one comment I have is that the conventional wisdom here in the US and Canada (the "standards" as they are being determined by the Tile Council of North America)is that a wire-reinforced unbonded mud bed should be on the order of 2" thick (50 mm). They tell us if we are doing a mud bed that is only an inch thick then we should bond it (to masonry substrates) or use metal lath (fastened to wood substrates) that is placed on the bottom of the mud bed.

 

[White Room]

You also have the insulation under the screed Rob

 

[Spud]

Hi Gary, I don't know all of the terminology that you and the rest of the guys have used in this thread, but one comment I have is that the conventional wisdom here in the US and Canada (the "standards" as they are being determined by the Tile Council of North America)is that a wire-reinforced unbonded mud bed should be on the order of 2" thick (50 mm). They tell us if we are doing a mud bed that is only an inch thick then we should bond it (to masonry substrates) or use metal lath (fastened to wood substrates) that is placed on the bottom of the mud bed.

thanks rob thats kind of confirmed what i was going to do as the bed thickness was thin ,I had another look at it today and I am now more confident than previously that repairing and bonding will work

 

[doug boardley]

only just seen this thread Gary (computer probs:mad2 what did you do?

 

[Spud]

here is what i am doing with the substrate ,repairing the cracks with epoxy resin and steel pins ,the cracks are cut out with a 4" grinder then pins are put in every 6" across the crack and then filled with epoxy this makes the repair stronger than the original screed

 

[Colour Republic]

I didn't realise it had cracked that much


It that what your finger looks like Gooner?

 

[Rob Z]

Nice work, Gary.

 

[Spud]

follow up pictures of problem substrate ,expanded metal mesh was placed through the mortar bed which varies between 40-50mm ,sbr bond was added to the mortar bed and bonding slurries ,60x60 porcelain centre feature with a 10cm border and a 90x45 field tile

 

[Colour Republic]

Looking forward to the finished pics Is that a wet UFH manifold?

 

[Spud]

Looking forward to the finished pics Is that a wet UFH manifold?

yes it is, that will all be inside some fancy built in furniture

 

[Colour Republic]

So what is that room for? Front room?
What mix is the mortar?
How far is the ufh under the tile?
Is that your bum in the picture?
If so, would you like me to get you some knee pads for Christmas
and lastly... Am i asking too many questions?

 

[Spud]

So what is that room for? Front room?
What mix is the mortar?
How far is the ufh under the tile?
Is that your bum in the picture?
If so, would you like me to get you some knee pads for Christmas
and lastly... Am i asking too many questions?

entrance lobby, 7:2 polymer modifed,between 70-80mm ,no and I have knee pad pockets in my trousers, and no you can never ask too many questions

 

[Colour Republic]

entrance lobby, 7:2 polymer modifed,between 70-80mm ,no and I have knee pad pockets in my trousers, and no you can never ask too many questions

Just checking, thank you

as you were

 

[Spud]

grouting done ,flexi grout ,just the downstairs loo and mat well to do in this method now

 

[White Room]

Nice panel in the middle, well planned out Gary

 

[Rob Z]

Nice work, Gary. It looks like you floated and set all in one shot. Do you have a mixer? We use a mud box and chop it with a hoe.

 

[White Room]

For small amounts of screed I use a plasterers bath mixed with an old belly drill, very slow mixing and with the right paddle

 

[Colour Republic]

This room still confuses me, if it's an entrance hall, where is the entrance? is it the door with the fire closer on it? or have we just not seen the main door yet? For an entrance hall that size the door doesn't look grand enough.

Sadly I don't think the pictures do the floor the justice is deserves I know in the flesh and an overall scale would look great. Stop being a tiler, get off your knees, and show us the job in it's full glory