Replies

1. 
   Piffin | Jul 06, 2004 10:30pm | #1

   Your last line will open a floodgate. I'll offer a couple brief comments and step aside.

   Whether it is necessary can oly be determined by an on site investigation by competant persons. if you feel less than competent to determine this, I want you to carefully ask yourself if you are capable of doing the forming and pouring safely. I am not trying to insult you, but to keep you alive. This is one of those things that is easy for those experienced, but totally danngerous for an inexperienced DIY.

   Once poured, in the summer, three days to a week is sufficient for cure time to load. Sometimes we pour, strip the day day, and begin building the following day in summertime, but for the type job you describe, I anticipate point loads from uneven settling and from using jacks etc. Those point loads can concentrate forces of the total load in one place which calls for strong cures.

   Code calls for PY or a barrier between wood and crete, so plan for that. No untreated wood should be in contact with the crete. If you are in a termite or ant zone, consider a copper flashing too and maybe treating the soil.

   Think slow and long, then work fast and hard.

    

    

   Welcome to the
   Taunton University of Knowledge FHB Campus at Breaktime.
    where ...
   Excellence is its own reward!

1. 
   Est1750 | Jul 07, 2004 01:23am | #4

   Thanks for the feedback.  I am not at all insulted as I want to get the job done correctly and safely and hence the reason I have posted on this forum.  I have decent experience in Roofing/Framing/Decks (did it for 10 summers with my dad), but have limited experience in concrete work (assisted pouring a couple of floors, sidewalks and poured numerous footings for decks).   I was feeling fairly confident that I would be able to create the form and mix and pour the concrete since I was only raising the wall 6 inches and didn't think this seemed like a complicated task, but it appears I may be underestimating the complexity.  I was also planning on drilling some holes in the existing stone/mortar foundation to put in rebar throughout the length of the wall to secure the new foundation to the existing one.  I would appreciate your thoughts on if you think I am making a mistake in trying to undertake this part of the project by myself and if not any additional suggestions/reference material you could point me to.  By the way, what does DIY stand for (I'm sure you'll have a field day with that question)

1. 
   Piffin | Jul 07, 2004 02:05am | #5

   DIY = Do It Yourself

   Only you know the extent of your own capabilities. I misunderstood apparantly on your first description that you were only lifting six inches tho'. I thought you were replacing the wall all the way down to and including footings.

   Easiest way to form and pour, in my mind is to jack the place up 9"-10", form six and then you have room to pour. The crete will likely shrink 1/8" to 1/4" while curing so let that happen before seating the house back down too. 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

2. 
   IanDG | Jul 06, 2004 10:40pm | #2

   Your solution to cast a concrete ring-beam on top of the existing stone wall is a good one but you will need an engineer to design the rebar and, as Piffin said, the formwork and concrete placement is not DIY.

   Curing time is totally dependent on temperature and humidity -- your engineer will be able to advise you better than we can, viewing it from here!

   IanDG

3. 
   SamT | Jul 07, 2004 12:45am | #3

   Depending on the chemistry, the engineering, the weather, and the skills of the contractor. . . from  1 to 14 days.

   SamT

   Arguing with a Breaktimer is like mud-wrestling a pig -- Sooner or later you find out the pig loves it. Andy Engel

4. 
   JohnSprung | Jul 07, 2004 04:04am | #6

   Concrete is generally considered to be up to full strength at 28 days, and the curve goes up fast initially then slacks off. 

   But for a footing, you don't need anywhere near fully cured concrete.  The concrete may be good for 2500 psi when it's done, but the wooden sill plate you put on it maxes out at more like 625 psi, and the actual weight of the building doesn't even get close to that. 

   I did this once, mixing the concrete myself in small batches.  Twelve hours of mixing mud and humping it into the crawl space.  The concrete was strong enough to put the house on before I was strong enough again to do it.  Figure on giving yourself some time to rest after the pour.

   -- J.S.