Extension floor build up

[HughF]

Providing I can figure a solution to get air to the air bricks on the back of the house, for ventilation under the suspended timber, how does the following build up sound:

 

75mm reinforced concrete with 16mm al-pex tied to mesh

slip membrane

140 pir

dpm

60 eps

sand blind

150mm type 1, whacked

 

Bought a job lot of cheap 140 pir on impulse the other night so trying to figure out how best to use it 😂

 

Will the bco be happy with that buildup given that we’re building over a sewer, the long way, all the way to our boundary.

 

This is a standard rear extension on an end of terrace.

 

 

Edited April 23, 2022 by HughF

[jayc89]

You could probably do away with the sand blinding given you have EPS under the DPM too. Where did you get the cheap PIR from?

[Russell griffiths]

I would want 100mm concrete minimum. 

[tonyshouse]

I hate sand blinding as it percolates through the hardcore like sand flows through an egg tier over time leaving voids 

 

min 100mm concrete, depending on size of the space could bev125mm.

 

 

[HughF]

On 24/04/2022 at 10:17, jayc89 said:

You could probably do away with the sand blinding given you have EPS under the DPM too. Where did you get the cheap PIR from?

My neighbours, who also bought it cheap and had it left over from a recent job. I come home to find a 5ft high stack of it on our lawn, wife says ‘neighbours are storing that there till someone collects it’ 😂 Neighbour comes home from work and a quick exchange is done… I’ll use it somewhere, sometime.

[HughF]

On 24/04/2022 at 20:51, Russell griffiths said:

I would want 100mm concrete minimum. 

I’ve got 100 in my garage and have high point loads (machinery), 100mm in a residential floor should be fine, surely?

[HughF]

5 hours ago, HughF said:

My neighbours, who also bought it cheap and had it left over from a recent job. I come home to find a 5ft high stack of it on our lawn, wife says ‘neighbours are storing that there till someone collects it’ 😂 Neighbour comes home from work and a quick exchange is done… I’ll use it somewhere, sometime.

I have a sneaky suspicion that they left in in my garden because they know I'm a sucker for a deal

[HughF]

Been getting used to using concepts on the iPad for sketching, this is the planned floor detail.