Building Homes or Extensions/concrete window sills

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Expert: - 6/29/2009


Question
I need to construct some concrete window sills that are 5 feet in length by 10 1/2 inches deep and 4-5 inches thick. If I cast these myself, what proportions of aggregate and portland cement should I use? Also, would it be necessary or a good idea to include rebar in the casting?

Answer
Dave, I would use 1 part Portland, 3 parts sand, 5 parts full graded stone by volume.  The sand should be a well graded concrete sand.  If you are casting these separately and then handling them, I would certainly give them rebar.  The shape is a bit prone to shrinkage cracking and will need to be cured properly.

The edges should be chamfered or eased.  The concrete should be vibrated.  The sill should probably be sloped.  You should have an anti siphon rustication in the bottom.

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Dan Griffin

Expertise

I can answer almost all questions related to the total construction process. My expertise is in commercial construction, though I can field most any residential question. I have hands on experience in concrete, heavy equipment, masonry, all phases of carpentry, interior finishes, and I am fairly strong in mechanical and electrical.

Experience

I have over 20 years experience as a commercial carpenter and commercial construction superintendent. I have another 20 years experience in facility management for a major school district.

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My favorite hobby for he past 12 years has been singing bass in a The OkChorale men's barbershop chorus and the Mature Moments quartet.

Education/Credentials
I hold a Bachelor's degree in English and Math. I have completed many continuing education hours in the building trades. I hold a Master Carpenter card from the AGC, Associated General Contractors.

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