Extension 10sqm foundation questions.

[Niklaspe]

Planning to build an extension of about 10 square meters and considering either doing a pier foundation or placing the joists on edge beams with insulation (hybrid foundation). Do you think it works to place an extension on edge beams that are 300x300 and 140x140 thick? Or is there a risk that they may be prone to tipping, even though the edge beams are locked together at the corners with chemical concrete or expanders?

 

[klaskarlsson]

I was mostly wondering how it's going with ground moisture?
You're building a crawl space (not sure what you mean by "hybrid"), so it's important to ventilate and lay a proper moisture barrier against the ground...

You could also use regular lecablock, right?
But edge elements probably work constructively, especially if you dig them down a bit?

Generally speaking, you should have the same foundation in the extension as the main building, so it also depends a bit on how that looks...

 

[Niklaspe]

No problems with ground moisture as you both insulate against the ground with 300mm and lay the moisture barrier. The only thing I want to know is if the edge elements need to be anchored (tied together) so they don't tip over from the loads of the extension.

 

[prototypen]

A regular wall or foundation piers will sink straight down IF there is settlement.
L blocks get uneven ground pressure IF there is settlement and tend to tilt.

Protte

 

[Niklaspe]

A regular wall or pillars will sink straight down IF there is a settlement. The L blocks get uneven ground pressure IF there is a settlement and want to tilt.

Protte

so you believe that even if you tighten the blocks properly, they can still tilt?

 

[prototypen]

Try using concrete barriers, like those used to close off pedestrian streets, as they are symmetrical and shouldn't tip over.

Protte

 

[Niklaspe]

Haha could have worked! But it felt easier to make a plinth foundation then and cover and insulate.