form ties

[billconner]

Pouring a sill in a door opening tomorrow - between/in line with stemwall - so I can install doors before floor and apron is poured. It sits on a footing to below frost anyway and I want a joint between it and slabs on ground anyways.

10' opening, 7" thick, about 10" wide. Can I get away with two-by tied to stem walls and a single form tie in center? I can pack gravel against forms as well.

Thanks!

 

[ConCretin]

A single tie in the middle of a 10' span might be OK if your form material is fairly rigid and it's secured at both ends. As a general rule of thumb for edge forms less than 12" deep, support 3/4" thick form material every 24" and 1 1/2" form material every 48". Support can be ties, stakes or braces. If your form bows, you can always add some support after the concrete is in.

 

[billconner]

Thanks LL! I'm thinking I'll put in some stakes, or nail a two by across and remove it after an hour and still be able to trowel or both.

 

[larry4406]

Install a taught string line along the the form board, secured only at the ends and leave it in place.

This is the guide for installing the form board straight initially as well as monitoring the pour for any outward bow that may develop.

 

[billconner]

Thanks all! Pour went well, if hectic and stressful for me. I stretched strings, added a block at center since forms bowed inward, and drove stakes at third points to prevent spreading. Sorry, no picture. Tomorrow.