Self Help Forums

Go Back   Self Help Forums > Building > Building Codes - Residential
Register FAQ Members List Calendar Today's Posts

Building Codes - Residential International Residential Code 2000 or 2003

Reply
 
Thread Tools Display Modes
  #1   IP: 71.254.213.28
Old April 6th, 2009, 05:14 PM
Masterofnone Masterofnone is offline
Junior Member
 
Join Date: Apr 2009
Posts: 7
Default Detached garage foundation

A couple of years ago I purchased a property in the country with an old mobile home and a detached garage on it. The garage is approx 20' x 30' with a concrete floor and a cinderblock foundation around it. The 2 x 8 sill plate for the garage is rotted so I'm going to replace it. At the spots where the sill plate has rotted away I can see down through the cinder block and there is no footing underneath it. I've driven a piece of rebar down through the openings in the block to confirm that there's noting underneath it but dirt. The mobile home that I live in is the same way. It has a concrete block foundation around the perimeter but no footing underneath it. Both the mobile home and the garage are more then 40 years old and in that time they dont seem to have had any structural problems other then the sill plate rot in the garage.

My question is.............was it once a an acceptable practice to build a block foundation without a footing ? Is there anything I should do to improve my garages foundation when I replace the sill plate............other then pressure treated lumber ?
Reply With Quote
  #2   IP: 148.78.63.154
Old April 6th, 2009, 07:33 PM
Wgoodrich's Avatar
Wgoodrich Wgoodrich is offline
Super Moderator

 
Join Date: Sep 2002
Posts: 7,451
Default

The Code back then was not a lot different than the Code rules today. Minor changes but same principles were used. However back then no one read the code. Today they are just learning the advantage of reading and learning the code. Then again when we have inspectors told they are to be seen an not heard in many local jurisdicitons and trained inspectors get the boot for trying to teach the industry the code we still have just the beginning of a learning curve when it comes to building design. You will find many garages in the nation built today same as you discribe. It does not meet code but in those jurisdictions most if not all really don't know the code. It seems the more we go ahead in professional skills the more we go back to the good old days.

In your case you are just planning to jack up your garage and replace the sill it would be a minor repair. If it was my garage I would fill the cinder block wythes with concrete installing anchor bolts every 6' closing those holes, creating a method to bolt the building to the foundation and protecting from the corrosive earth conditions. Then install an aluminum shield over the blocks then use treated lumber.

If you want to know the code and the building being only 600 square feet the footer is supposed to be installed 12" under ground then the blocks laid so the top of the foundation is 12" above the flat earth. Then 6" of dirt is supposed to be installed ensuring 6" of fall in 10' away from the building to shed water from the building. Then you will have a building lasting beyond life expectancy of your children.

Good Luck

Wg
Reply With Quote
  #3   IP: 71.254.210.218
Old April 8th, 2009, 03:13 PM
Masterofnone Masterofnone is offline
Junior Member
 
Join Date: Apr 2009
Posts: 7
Default

Thanks for the response WG. I hadn't even thought about using an aluminum barrier between the block and the sill plate. I was just going to use some tar paper. Aluminum sounds like a better idea.
Reply With Quote
  #4   IP: 67.66.143.175
Old April 10th, 2009, 10:33 AM
Sean Sean is offline
Junior Member
 
Join Date: Mar 2009
Posts: 8
Default

The aluminum flashing is also known as termite flashing. As termites work their way up through the foundation walls (either through the empty spaces in the cinder blocks or through cracks in a concrete foundation) they hit the layer of aluminum flashing and are forced to the outside of the wall where they will create little tracks that are easily seen, and thus you know you have a termite problem and can call the exterminator. This also prevents them from eating through your sill plate.
Reply With Quote
  #5   IP: 148.78.63.154
Old April 10th, 2009, 12:48 PM
Wgoodrich's Avatar
Wgoodrich Wgoodrich is offline
Super Moderator

 
Join Date: Sep 2002
Posts: 7,451
Default

You want to let the aluminum hang out 1" past the wall flying in the air. Termites can not stand daylight. They die when exposed to open air. Termites are a team effort. Many termites will commit suicide trying to build a tunnel to protect fellow termites to their dinner plate. The 1" gap lets them build the tunnel but they can't make the sudden U turn to get to the top side of the aluminum without going to daylight thus they give up and lost dinner aka your wood. Also an added fact about termites. The queen of a nest may be located as much as 100 feet underground having the workers branch out all over a town from that one nest. Now you know, Hee Hee.

Just added info

Wg
Reply With Quote
  #6   IP: 71.254.210.181
Old April 23rd, 2009, 05:17 PM
Masterofnone Masterofnone is offline
Junior Member
 
Join Date: Apr 2009
Posts: 7
Default

My garages block foundation only comes to ground level along the one side. In fact, the interior concrete floor is about 1 1/2 inch higher then the top of the block. The top of the sill plate is level with the interior floor.

Please give me some feedback on this idea;

instead of just replacing the sill plate, maybe I should raise my foundation wall another course of block a section at a time. I could just shorten the height of my walls by the height of the additional block. Then my new sill plate will be higher up off the ground and I'd have a course of block to deflect surface water.

good idea or bad idea ??
Reply With Quote
  #7   IP: 4.224.147.245
Old April 24th, 2009, 09:19 AM
Wgoodrich's Avatar
Wgoodrich Wgoodrich is offline
Super Moderator

 
Join Date: Sep 2002
Posts: 7,451
Default

What you discribed is the reason you had rotted sill plates. Surprised the untreated wood studs are not also rotted.

The Code requires a minimum of 8" from untreated wood and the finished grade. If it were me I would jack up the entire builting and raise the foundation enough to obtain 6" fall in 10' around the building flowing water away from the structure. I would use solid blocks mortared in place and install anchor bolts to secure the structure to the new foundation after is has cured. I would install the aluminum with a hangover for termite protection between the block and the sill plate.

Now that said if you only replace the sill plate with treated lumber it may last you another 10 years or so. Short cut or doing it right is up to you, it is your building.

Good Luck

Wg
Reply With Quote
  #8   IP: 71.254.210.181
Old April 24th, 2009, 05:08 PM
Masterofnone Masterofnone is offline
Junior Member
 
Join Date: Apr 2009
Posts: 7
Default

Thanks again WG. You've been a huge help. I don't think I want to take any short cuts.
Reply With Quote
  #9   IP: 121.246.155.201
Old May 11th, 2009, 02:07 AM
jyothi jyothi is offline
Junior Member
 
Join Date: May 2009
Posts: 1
Default Detached garage foundation

I've driven a piece of rebar down through the openings in the block to confirm that there's noting underneath it but dirt. The mobile home that I live in is the same way. It has a concrete block foundation around the perimeter but no footing underneath it. Both the mobile home and the garage are more then 40 years old and in that time they dont seem to have had any structural problems other then the sill plate rot in the garage.
Reply With Quote
  #10   IP: 148.78.63.154
Old May 11th, 2009, 06:37 AM
Wgoodrich's Avatar
Wgoodrich Wgoodrich is offline
Super Moderator

 
Join Date: Sep 2002
Posts: 7,451
Default

100 years ago in my town they built homes laying brick made on site right on the grass. The homes built 3 or more decades ago were smaller houses 600 to 100 square feet. Now we have 3 story homes built a lot heavier. Those older homes most often were built with native lumber that turned hard as steel in a few years. All this makes a difference today versus yesteryear. Many of the older homes have sill rot and floor joists morticed into the 12x12 beams finding those floor joist tails to also rot. There are problems today with many of those older homes that progressed over the years.

Even today a mobile home is so light and if placed on a mobile home lot is allowed to be supported without a footer and just stacked blocks. If permenantly set on private land the same structure is required to be with a footer and mortar laid blocks. The difference if mobile home lot is considered temporary setting, private land permenant setting.

Just some info on the subject

Wg
Reply With Quote
Reply






Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -4. The time now is 02:17 AM.


Powered by vBulletin® Version 3.6.7
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
© 2002 - QuinStreet, Inc.
http://www.selfhelpforums.com