sand and cement screed (very dry pug mix) weight calculation.

[pappasmurf]

Hi, I am having underfloor heating put in into my sisters house on the 2 upper floors of the house. the construction of this UFH system is as follows:-

• Battens put in-between the joists
• 50mm Kingspan foiled insulation boards placed inbetween these joists
• UFH pipes circuit run on top of these boards
• 30mm of sand and cement screed (very dry pug mix 5:1) applied ontop.

I need to calculate for structural purposes the "weight" of this screed, to see if my joists/ building can take this weight without any other structural supports.

Would anybody know what the weight/m2 would be for the spec I have just given "without" involving an expensive structural engineer ?

 

[SFK]

Density of DRY sand is about 1,550kg/m³
Cement is about the same.
But will fill the voids in the sand.

So I would GUESS about 1,900kg/m³ to 2,000kg/m³
Use lower number to ignore wood.

(Poured Concrete is 2,400kg/m³, but that is denser as it has no air voids and lots of reacted water).

https://www.google.com/search?q=dec...hUKEwi8yaDEnsTvAhWoQUEAHT_ZDwYQ4dUDCAw&uact=5

So weight in a room in KG is = 1,900kg/m³ x 0.030m (depth of screed in m) x width of room (in metres) x length of room (in metres)

Quick test:-
as an example, for a 3m by 4m room with a 30mm screed...
weight (kg) = 1,900kg/m³ (density) x 0.030m (depth in m) x width of room (in metres) x length of room (in metres)
weight (kg) = 1,900kg/m³ (density) x 0.030m (depth) x 3.000m (width) x 4.000m (length)
weight (kg) = 1,900kg/m³ x 0.03m x 3m x 4m
weight (kg) = 1,900kg/m³ x 0.36m³
weight (kg) = 684kg


To be slightly more accurate, for width or room remove the width of joists.
For example a 4metre wide room might have 10 joists each of 4cm.
So width of Screed is 4m - (10x 0.040m)
So width of Screed is 4m - (0.400m)
So width of Screed is 3.6m



SFK

 

[conny]

Can I just ask where are the electrics running for the downstairs lights?
Have you enclosed them in conduit or are they simply laying between the joists under the screed?
Not being funny but people have been known to do silly things when looking at the bigger picture and forgetting the 'minor' details.