Footings on bedrock?

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  #1  
Old 05-31-04, 10:01 AM
slotspuller
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Question Footings on bedrock?

I'm trying to decide how best to make footings on exposed (and slanted, to boot) bedrock. At least two of the footings will be in a spot where the rock slants a good 45 degrees (the others are maybe 15-20 degrees) away (down) from the house. My original idea was to drill and set pins in the rock, spend hours cutting 12" sonotube to the right contour , and set U-brackets in the concrete. Option two was to use a square-ish wooden form, and place deck blocks in the setting concrete. Does anyone have better ideas or suggestions/thoughts on the two methods I'm contemplating? The deck itself will be about 16x26, attached to the house at the long dimension, with the tallest posts about 4' tall. I hope someone can help me decide on the best way to do this as my wife is getting impatient for the work to begin...
 
  #2  
Old 06-03-04, 12:11 AM
L
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slotspuller,

Welcome, and I have no idea. It's not a situation I have ever had to deal with before. Best bet would be to ask your local bldg. dept. If you have bedrock in your yard, those guys HAVE dealt with it before and know what works and what doesn't. (They also know what they will accept and what they won't!!)
 
  #3  
Old 06-03-04, 09:48 AM
slotspuller
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Smile

Thanks, Lefty, for the suggestion. I already talked with people at the local yard, and also to a contractor, and didn't get a definitive answer. The contractor said "no problem", just build forms and pour concrete. The guys at the yard said I need to drill 1/2" holes in the rock and insert sections of rebar so they extend into the concrete to provide an anchor. All fine and good, but the bedrock is granite, so drilling is going to be a major chore. I don't even know if I can do it with consumer-grade equipment. I guess I'll have to try to see if it's possible. My fear is that my half-inch hammer drill will just dent the surface. I tried a grinder with a masonry wheel, and all that happens is the wheel gets smaller... I could hire a drilling contractor, but am loathe to do so since it would be expensive and would delay construction further. Besides, this is supposed to be a DIY project.. If anyone has any thoughts, I'd really like to hear them. Maybe I'm making much todo over nothing and can just pour the footings without creating anchors.
 
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Old 06-03-04, 07:58 PM
L
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The contractor, the yard guys -- that's NOT the answer you need! You need to get to the BUILDING DEPT. and see what THEY will accept, and go from there. If you have these rocks in your yard, they are all over the area. Those guys have been dealing with the situation for years!
 
  #5  
Old 06-04-04, 01:44 PM
slotspuller
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Red face

Geez... I just re-read your original reply and see that I need to take some reading comprehension classes... I thought you said building supply store. You are absolutely right, the building department should be able to tell me what is required according to the building code. I'll check with them and hopefully they'll have the answer. Thanks for the tip.
 
  #6  
Old 06-09-04, 12:28 PM
slotspuller
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Followup...

Well, the people at the Building Department were basically unhelpful. They seemed to be more interested in the size of the deck and if it was or wasn't attached to the building, i.e., so they could re-assess the property for additional taxes. They said concrete footings poured on the bedrock are fine. But I decided to forget about the concrete entirely. Since I planned on drilling into the rock to insert "pegs" as concrete anchors, I figured I may as well just use post saddles and bolt them directly to the bedrock. I tried the hammer drill and it works more or less OK. It's slow, but does the job. Using the saddles will save me building forms and mixing concrete, so I'll save some time and money going this route.
 
 

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