14,344 views ·
16 replies
14k views
16 replies
How to attach the sill plate to the cement slab.
In several construction descriptions, you can read that the sill is attached with an expansion bolt in slab on ground. With underfloor heating, it feels a bit inappropriate. I've started considering casting a threaded rod into the slab, placing the sill in position, hammering with a large hammer and drilling at the marks. Then add sill sealing and sill, secure with a washer and nut. Or even simpler, rebar protruding, hammer, drill, add the sill and bend the rebar. How have you solved this? There may be other solutions.
But the underfloor heating shouldn't be placed under the walls, right?
The best thing is to avoid having the heating cable right there. Otherwise, I would embed a threaded rod. A welded nut at the bottom plus a large washer so that the rod gets a good grip and then cling film or similar over the threads during casting.
What is relevant is at what depth the underfloor heating pipe is located.
Do you have photographs from the casting or other documentation?
My experience is that you should not rely on there not being underfloor heating pipes under the walls; your fastening to the slab is mainly to prevent the wall from moving sideways, and therefore you do not need to fasten the wall so deeply into the slab, usually 20-25 mm is enough, and that is often covered with the concrete cover above the reinforcement. But as I said, I was not involved in casting your slab, so I do not know. But get back to me with the depth of the underfloor heating and what type of sill plate you will be attaching, and I will be happy to help.
Do you have photographs from the casting or other documentation?
My experience is that you should not rely on there not being underfloor heating pipes under the walls; your fastening to the slab is mainly to prevent the wall from moving sideways, and therefore you do not need to fasten the wall so deeply into the slab, usually 20-25 mm is enough, and that is often covered with the concrete cover above the reinforcement. But as I said, I was not involved in casting your slab, so I do not know. But get back to me with the depth of the underfloor heating and what type of sill plate you will be attaching, and I will be happy to help.
Excuse me, forgot an addition... however, there is no point in casting in threaded rods and other cumbersome solutions since there are so many convenient products for this particular purpose on the market. A sill never experiences such stress that such strong anchoring is needed.
The underfloor heating lies so shallow here that you should already mark out interior walls to ensure you don't drill into the pipes later; it looks like you should manage with the exterior walls anyway, right? Kartro has a screw called husskruv for the sill, you just drill through the joist and down into the concrete then you drive in the screw with an impact wrench, works brilliantly.
The best approach is to take a reference point that will stick out until the end, then take photos with a ruler or similar laid out so you can locate the pipes.
It has helped me tremendously with all the pipes in the house. Just seeing how it looked and having the measurements makes it easier to remember. A number on a piece of paper doesn't indicate if you measured to the edge/center/front/back.
And the answer to the question is that I used nail plugs, quick and easy.
It has helped me tremendously with all the pipes in the house. Just seeing how it looked and having the measurements makes it easier to remember. A number on a piece of paper doesn't indicate if you measured to the edge/center/front/back.
And the answer to the question is that I used nail plugs, quick and easy.
Doesn't really relate to your question but in the picture, it looks like the hose is placed on top of the reinforcement, with the associated risk that it might float up during casting. It's usually better to hang it underneath so it can't float up if some wire comes loose or if something was missed somewhere.


