Broken anhidrite screeds

[diamondtiling]

I have around 12 broken screeds on the job I am on at the moment. These are all caused by other trades working on them before they have fully cured or by other unforeseen curcumstances.
I need to know if I can cut out this damage and replace with something that will allow for the UFH below? Will these screeds knit together and stay bonded?
I will post some pictures tomorrow.

 

[White Room]

Thats for Ajax that one.

 

[DHTiling]

These are a strong screed and i cannot see how they have broke one..?.. and wtf are they doin walking on a wet screed.?.. is this a pour fault..?

 

[nybor62]

as above ' or maybe stood to long before they started pumping it in ,

 

[diamondtiling]

I dont think it a pour fault Dave, all the cracks and damage are at the apartment entrance. These were shuttered in but I think the shuttering was removed too early and thats where the damage happened.
I also dont think its the screed itself, each part is very strong, not crumbly at all.
Will post pictures later.

 

[DHTiling]

Shuttering ? This gets worse lol

How big an area and are there perimeter joints and doorway joints

How soon after the pour was it walked on


Sent from my iPhone using Tapatalk

 

[diamondtiling]

Dave the shuttering was at the only entrance into the apartments, these were fixed by UK screeders across all the doorways so I suppose they were required, actually if you had watched the pour then you would have seen just how liquidified the screeds were, no shuttering and the communual hallways would have been full.

On a site you can have people walking on freshly laid floors within minutes regardless of the large sign warning to stay off.

As mentioned previously I will post pictures later, that will make this thread a lot easier to explain.

 

[Aston]

sounds definately as though the fault is due to people walking on the screed before its set. 48 hours is the usual minimum time.
because the screed is over under floor heating and not a bonded screed, then this is going to be more tricky. they can be reparied but more info would be needed...

were stress relief joints used at the threshholds
what depth was poured??

i have a contact at csc screeds who will gladly help you out. if you need his name and number, then let me know. they are experts in floors screeds and they'll put your straight. you'll be able to send them photos etc

best of luck
ed

 

[sgd tiling]

the floor wasnt compressed enough,plus the sreed always breaks up at walls n door entrance,moisture is taken oot sreed at walls due 2 plasterboard,door entrances they should ave shutter at the finish,2 fix cracks on floor latex

 

[Spud]

you can stitch repair it using epoxy resin and stainless pins

 

[Ajax123]

It is very repairable generally but depends on several factors not least of all the cause of the cracking. I would like to see some pics before commenting further. If you are able you should take some pics in cross section of the screed to show the depth and also if possible give me an idea of the floor make up and the insulation type, when it was screeded etc etc . The more info the better to be honest but I understand some of this might be difficult so a picture can say a thousand words. If you don't want to publish in the forums the project details send me a P.M....it may well be one I have been involved with myself.

 

[diamondtiling]

One picture shows the sub floor of a typical apartment, this has foam type insulation fitted and the UFH fitted over it. The screed is tarmac topflow and is approximately 50mm thick. Before anyone asks I am not laying these screeds or recommending them, that is all down to the architect. I just have the problem of mending the damage before fixing. UK screeds are saying that they laid the screeds in accordance with Tarmacs methods. I think they are pretty thin although they do seem very strong.

One floor out of some 230 failed and was removed by the contractor at their expense.

 

[Ajax123]

Oh my lord what a mess some of those are. I would suggest that the best thing would be to cut back some of the screeds to form nice neat edges then re-instate using bagged Gyvlon screed. Tarmac Truflow is a Gyvlon based screed so the two are fully compatible, You will need to prime the open edge of the old screed first though. If you need to know where you can get this from PM me.

The cracks look to me like they are at points of restraint or near to where the screed should have been jointed. There is little point in repairing these cracks unless something is put in place to control movement under thermal loadings. The screed should have joints at door thresholds, between independent heating zones and points where unheated meets heated. Additional joints should be placed where the aspect ratio exceeds 8:1 - e.g. long thin corridors of which you appear to have several. The screed should be a minimum depth to allow 30mm cover to any underfloor heating pipes. typically this would mean a minimum 45mm but nominal 50mm.

It also looks quite damp....when was it screeded??


NO coverings should be applied until after the underfloor heating has been comissioned and run. The screed also looks like it will need the surface cleaning up.......a rotary floor sander with medium to coarse paper should suffice......this will also remove any surface laitance. Laitance should be removed before the heating is run if possible as it will become harder if left in place. If you need a contact for Tarmac who would be able to advise further again PM me.

 

[diamondtiling]

Hi Al and thanks for your reply. None of these floors have been heated prior to the tiles being fitted, that again is not my decision but the Architects. Norcross have supplied the matt (thermalay) that they say will stop any de-coupling.
The 7th, 6th, 5th, 4th and 3rd floor have all been turned on and run at full temperature for some two weeks without any problems (yet)

There is no point in me trying to get this part of the job done before tiling as it comes under the Architects say so. I do have a machine on site for removing the laitence, they then get two or three coats of sbr prior to tiling.

I will take your advice regarding the repairs. Those particular screeds have been down for 3 weeks, we have another 70 to do which are due to be laid next week.
Pm me your mobile number please Al and i will call you on Monday if thats ok?

 

[Ajax123]

Hi Al and thanks for your reply. None of these floors have been heated prior to the tiles being fitted, that again is not my decision but the Architects. Norcross have supplied the matt (thermalay) that they say will stop any de-coupling.
The 7th, 6th, 5th, 4th and 3rd floor have all been turned on and run at full temperature for some two weeks without any problems (yet)

There is no point in me trying to get this part of the job done before tiling as it comes under the Architects say so. I do have a machine on site for removing the laitence, they then get two or three coats of sbr prior to tiling.

I will take your advice regarding the repairs. Those particular screeds have been down for 3 weeks, we have another 70 to do which are due to be laid next week.
Pm me your mobile number please Al and i will call you on Monday if thats ok?

07545 932723. It is a works number so I am not too worried if it appears on here mate.