Sand and Cement screed reinforcement?

[bissoejosh]

Assuming a non structural 85mm sand and cement screed how do I determine if I need reinforcement mesh/fibres or nothing at all?

 

Buildup:

 

Beam and Block

Sand blind / EPS

DPM

150mm Kooltherm K3

Seperation Layer

85mm Screed with UFH

 

Many thanks

 

[nod]

Your as well ordering the screed with fibres in 

and making sure you have a joint at each doorway 

[epsilonGreedy]

1 hour ago, nod said:

Your as well ordering the screed with fibres in 

 

 

In another thread @PeterWmentioned fibres don't add much to the cost, < 10% extra per ton.

[epsilonGreedy]

1 hour ago, nod said:

and making sure you have a joint at each doorway

 

 

I have been thinking about this but did not realize it was a known construction option. Can the joint be formed using the same material used for floor screed edge insulation?

[Mr Punter]

9 minutes ago, epsilonGreedy said:

Can the joint be formed using the same material used for floor screed edge insulation?

 

Sometimes they use a tool to create a slot in the screed while it is still green

[epsilonGreedy]

Since posting I have been wondering if there is a downside. If such a slot encourages movement to occur at the slot and UFH pipes run through the slot is there a danger of local stress fatigue to the pipes at that point? 

[PeterW]

9 minutes ago, epsilonGreedy said:

Since posting I have been wondering if there is a downside. If such a slot encourages movement to occur at the slot and UFH pipes run through the slot is there a danger of local stress fatigue to the pipes at that point? 

 

Highly unlikely given the expansion of screed per mm/C change and you’re talking about a crack or slot that is 1-2mm

at most and is then filled. At approx 10 millionths mm/degree, a 10m slab will expand less than 2mm for 20c rise which tbh would be absorbed at the edges if at all.  

[nod]

Some screeners will run ther trowel through the screed on each doorway 

I always use a plastic screed joint 

10 x100 mill Cheap as chips 

They are just strips of double wall 

Cut the excess pod afterwards 

[epsilonGreedy]

1 hour ago, nod said:

Some screeners will run ther trowel through the screed on each doorway 

I always use a plastic screed joint 

10 x100 mill 

 

Something like this?

 

https://www.drainagesuperstore.co.uk/product/kform-k85-screed-rail.html

 

Or?

 

https://www.premiumtiletrim.co.uk/product/p-v-c-plastic-screed-expansion-joint-msr--beige-insert--by-genesis

[nod]

Yes 

To be fair the ones that we use are jus an 8 x4 sheet ripped into 100 s 

just saves the screed cracking in every doorway 

 

[Simplysimon]

sorry to highjack post, if i screed prior to kit going up do i need expansion gaps? thought it would be easier to lay sand and cement rather than barrowing in through doorways.

[epsilonGreedy]

46 minutes ago, Simplysimon said:

sorry to highjack post, if i screed prior to kit going up do i need expansion gaps? thought it would be easier to lay sand and cement rather than barrowing in through doorways.

 

 

I asked a related question about laying a ground bearing garage floor slab and was told that pouring concrete into a pool formed from a one block high perimeter wall would simplify the process. Not sure why you think such an alternative floor creation workflow influences a decision over door threshold expansion joints.

 

Will you be fitting UFH? I ask because I am thinking of the Grand Designs Graven Hill lady who suffered frost damage because cold weather got her UFH pipes due to a delay in creating a weathertight shell. Less of a concern for you given the current time of year.