Joining Wood to Masonry


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Old 06-02-07, 08:45 PM
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Question Joining Wood to Masonry

Can anyone advise a good reference source on joining wood frame to masonry?
Example - What is the technique for interior framing joining to a concrete block wall? DO you need a vapor barrier between the concrete and wood?
How are the trusses / rafters secured to the block wall?
What if some inside walls are the concrete block and join other wood interior walls?
Project not begun yet, just trying to understand the theory.
Cheers
 

Last edited by mking; 06-02-07 at 08:51 PM. Reason: to clarify
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Old 06-02-07, 09:04 PM
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Could you provide more specific info as to what you are up to and what your DIY project is? Once you tell us what you are trying to do the pros here will be all over your question. Theory is one thing & real life is another.
 
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Old 06-03-07, 12:21 PM
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In general, any joint between wood and masonry must be a soft joint. A structural soft joint between wood and masonry is very project specific. A non structural soft joint between wood and masonry is the standard joint design for elastomeric sealants.
 
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Old 06-03-07, 12:41 PM
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Joining Wood to Masonry

As noted above, the attachment methods are dependant on the specific details and what you want to achieve.

You are trying to attach two dissimilar materials that have different properties. Concrete is a very stable (temperature and moisture) material with a high compressive and shear strengths. Wood is an unstable material that is suceptible to changes in moisture, shrinkage and long term creep or distortion.

A vapor barrier has little to do with the method of attachement. It depends on the desired performance and the other materials since "vapor barriers" are only vapor retarder. Even a latex paint can be a "vapor barrier".

The attachment of wood trusses (or any roofing system) to a block wall are very elementary and covered in all building codes.

Probably the best source that you can find in the buidling codes that you will ultimately have to comply with yourself if you do not have a professional designer.

If you want specific answers to detail, post the complete situation in detail.

Dick
 
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Old 06-03-07, 03:14 PM
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Cool Joining masonry to wood

We are planning to move to Arkansas and do not want to purchase somone else's nightmare. Will not have mega bucks to spend and were looking at some of the manufactured homes but were cocerned with the strong formaldehyde fumes. Was considering building from scratch and wanted to use concrete blocks for foundation. Siince this will be in a tornado zone, wanted to put the garage underground to double as a storm shelter. Started to draw up the plans and realized I had no idea of how to join wood to concrete other than the use of J bolts cast into the concrete and bolted to the mud sill. Presume metal brackets are available for securing trusses / rafters. Have seen adobe blocks and cement block interior walls that were attractive but would want some interior walls to be wood or sheet rock. Suppose studs could be power nailed to the block wall. I plan to be my own contractor and hire qualified workers to assist. Building codes will not be useful since no permit or inspections are required except for the septic system. Was hoping somone would know how to join a masonry chimney to a wood frame wall, or are they both free standing? Believe it or not, it is possible to build in the U.S. correctly without the expensive nuisance of political beaucracy.
 
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Old 06-03-07, 05:19 PM
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Joining Wood to Masonry

mking -

Your first mistake is in ignoring the building codes. Whether they are enforced or not, they are the minimum standard of construction for a reasonably built structrure for someone to live in and expect to sell some time in the future. Building according to the least acceptable standard only makes sense.

With that out of the way, the only choice is the selection of materials. - You can build out of wood or use more permanent materials. There are established methods for connecting dissimilar materials and it is done every day according the generally accepted methods. - Do not try to "micro-manage".

If you want to build cheap initially, use a proper designed foundation since, you will not have a chance to make changes. Above grade, you have many choices - wood frame, masonry or poured concrete (ICFs are now popular). Masonry has been the tradition in the hurricane areas of Florida. After that you can apply any interior or exterior surface you choose.

Many people are correctly concerned with "safe cells" from either a tornado or hurricane standpoint. Visit the FEMA site to get the recommendation for appropriate construction. They apply to both above ground and below grade appilcations. The designs are well thought out and based on testing of debris pentration. The two wall construction methods accepable are either reinforced concrete or block. - Some people use either closets or bathrooms as "safe cells" because of the typical locations. Some use the entire home as a "safe cell".

Dick
 
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Old 06-04-07, 08:45 PM
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Joining Masonry to Wood

Thanks Dick
Appreciate the info but you failed to supply the critical info. Generally accepted methods of joining dissimilar materials are available - What are they? ? ?
I recognize you cannot cover every event, but can you recommend a publication I can obtain which will explain the various methods of attachment for various materials. As for the safe cell, I paid a civil engineer $500.00 for a plan for a foundation for a mobile home in the desert. He came up with a plan for concrete thirty inches high and twelve inches wide. My well is 360 feet deep and sand all the way to the bottom. We are in earthquake territory. Do you know what happens to sand during an earthquake ? IT LIQUIFIES. Recent news reveal entire houses destroyed by tornados but residents survived in the basement. Common sense trumps surveys always. Anything above ground is subject to destruction by an angry tornado. A bathroom or closet is better than nothing, but a hole in the ground is better yet. I do not plan to build cheap - just smart. The building inspector would have approved the 12 inch foundation - I threw away the plans and built an 18 inch T footing
 

Last edited by mking; 06-04-07 at 08:51 PM. Reason: To complete
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Old 06-05-07, 12:54 PM
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Joining Wood to Masonry

The FEMA "safe cell" is avaiable to the public on the FEMA site. It is detailed and can "spoon feed" you to follow it in detail and build what has been proven to be successful. You can obviously do it cheaper with less results. Apparently, you did not look at the available information in detail.

If you visited the FEMA site you would see how proper foundations can provide the stability for tornado resistance. I don't know what kind of protection you think that you can get from a 18" "T footing". A "safe cell" can be constructed within a home above grade or in a basement.

You are confusing tornados and seismic activities, which are totally different, just as tornado protection is different from hurricane protection. - Been through the Katrina/Rita thing and saw the differences between the hurricane winds and the mini-tornado winds that were spawned inland. That is separate from the storm surge results during my investigations.

Sand does not necessarily "liquify" during seismic activity unless it has recently been disturbed or has an available immediate moisture source to reduce the intergranular pressure.

A simple concrete masonry home on a proper foundation will provide many times the general protection from tornadoes than a wood frame home. Typically, you would have vertical steel and grouted cores around doors and windows and some intermediate points to make sure you have a maximum of 4' spacing. Use a bond beam around the top with anchor bolts to attach a top plate. Them attach the roof trusses in accordance with the local code requirements. You are permitted to attach them better since the roof connection is typically the weakest point.

If you want an answer, ask a question and provide the details and conditions. This includes the seismic factor you failed to incude. Not all of Arkansas is really in a major seismic zone. One the area near the "big one" really has the historically proven potential. I would be more concerned with tornadoes.

If you want to attach wood to concrete, it depends on what the conditions are. If the concrete is in contact with the soil, you must use treated lumber and the appropriate chemically resistant fasteners because of the wood preservative. If the concrete is not in contact with the soil (generally above grade) you can use any of the very common mechanical attachments ranging from anchor bolts down to nails. You may also use adhesives (or both) depending on the type of and magnitude of the loads.

Do not avoid the codes just because they are not in effect in your remote area. They are based on results and facts and contain a lot of good information. Just keep in mind they are MINIMUM standards and there may be better ways of solving the problem that can the allowed.

Dick
 
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Old 06-06-07, 10:02 AM
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Smile Joining Wood to Concrete

Thanks Dick. Did not mean to mislead you on the "T" footing, just citing an example of a Civil Enngineer and Building Codes which did not consider the possibility of liquification. On the safe cell, seems a waste of valuable living space if it can be done in an underground basement / garage. Steel reinforced concrete block walls also double as foundation is secure and economical. Want to include as much safety as possible in the plan and though we will be primarily concerned with tornados, there is still the New Madrid Fault which releases every 400 to 600 years - last time about 200 years ago so no lost sleep. Most of the subsurface in Arkansas is rocky. Saw an interesting test done in San Francisco with steel rods anchored in concrete foundation and extending between the studs through top plate and bolted down. Survived several shocks while same wall without steel rods twisted and collapsed.Plan to use prefab trusses for roof and can probably find metal brackets at Home Depot to attach to walls.
Thanks again
 
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Old 06-06-07, 11:31 AM
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Joining Wood to Masonry

You can't be very serious about seismic if you are considering using "off the shelf" trusses and attachments from HD. Those are the worst you can legally use and not what you need for real seismic activity.

What you saw in San Francisco, was an attempt at a semi-post tensioned wood wall or just trying to keep a wood structure together and on the ground.

Many people build safe cells (reinforced block with a concrete ceiling) as walk-in closets and do not lose space if they are building without a basement. Just follow the FEMA suggestions. Wood provides no protection from tornado projectiles like your neigbors home, patio and furniture.

If you are really concerned about seismic, hire a professional.

Dick
 
 

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