Clay bricks are baked in a kiln. Is it O.K. for an untreated girder to rest on a brick?
False
Marcel
Yes and No.
Depends how long it was fired and what the design water absorbtion rate is after it’s firing process. Solid or cored?
Too many variables in your question.
Marcel 
OK, how about a bazillion year old rock. It is O.K. for an untreated wood girder to rest on a rock?
Any wood sitting on cementicious based materials, should be protected by a moisture barrier.
In Canada, most provinces have it in the building code to place a moisture barrier between any wood and cement based products.
Concrete is the worst as it has the least amount of air space in the product,but even brick or block all will wick up some moisture if it is contact with soil over time.
It is not the initial moisture from the construction as some feel, it is the ongoing wicking that will cause the problem.
Concrete does not pull moisture from the air as some feel. If you see multi level concrete structures, it is always the ground units that have the decayed wood. Only some structural problems would allow water in the concrete several levels above ground.
David,
Then you are saying that an untreated wood girder which supports the second floor joists (well above grade) resting on a bazillion year old stone, is not a problem?
If it is a problem, why is it a problem? The stone can neither wick up moisture 8 feet, nor is it releasing mositure from the curing process as it is a bazillion years old already.
Once again, there should be a moisture barrier… are you sure it is a bazillion years old? If it is only several billion, this will make a huge difference!!!:mrgreen: :mrgreen:
If you know how mold grows and what ingredients are necessary, you would know that it would not matter on what a piece of wood bears on as long as the food and moisture are eliminated.
I have seen many houses built on stone foundations with the sill plate directly on the stone or brick with no evidence of rot or decay.
Eliminate the moisture intrusion and problem does not exist.
Last house framing I have seen was built in 1875. Wood looks like the day it was installed.
Marcel 
Nick,
Many times old buildings have wood embeded in old stone, mortar foundations. The ends rot as it is low to the ground.
In many old buildings you see literaly made of stone with huge wood beams on the second or third floor, there is no decay.
It is just good building practise to protect all wood today. In some areas it is actually code to separate them.
Exactly Marcel,
It is the moisture intrusion, not the moisture that was around it when installed. Concrete curing is not the same as concrete drying. On a hot week in July, the concrete can go from soup to absolutly dry. It will still take 28 days to obtain the working strength.
After that it is the moisture that is allowed to intrude into the concrete over time that will affect the wood as well as the rest of the structure.
I’m not arguing as to whether or not the contact should be protected… I’m asking where the moisture comes from. Anyone who has inspected rustic homes has seen the ends of wood girders or joists that are in contact with stone walls (remember, stone does not have left over moisture from the curing process) all rotted out.
David is correct that those situations that are closer to the ground (like in a crawl space) are worse… but why? Where is the moisture coming from if not from the curing process and not from wicking up moisture from grade?
We should not be advocates of having lumber bear on any masonry, concrete, nor stone foundations in todays World of Science as we know it today.
Any lumber in contact with whatever material that is susceptable to moisture intrussion by wicking or cohesion should be treated for moisture protection.
Even structural steel beams and miscellaneous metals wether painted or not should have treated wood if it is in contact.
Marcel
Sometimes with older houses the grading does not direct the water away from the foundation. This moisture is part of what is wicked into the foundation wall. While the stone may not contain moisture, the mortar will, especially the old lime based mortar. It will pull vast amounts of moisture.
Also old stone wall can absorb water from the weather if not protected well.
[quote=gromicko]
I’m not arguing as to whether or not the contact should be protected… I’m asking where the moisture comes from. Anyone who has inspected rustic homes has seen the ends of wood girders or joists that are in contact with stone walls (remember, stone does not have left over moisture from the curing process) all rotted out.
quote]
Moisture Vapor Diffusion and Ventilation Deficiencies.
Marcel:)
You are getting close. I’ll give you a hint…
A stone house has a stone fireplace in the middle. The girders and joists that hold up the second floor are rotted where they penetrate the exterior walls, but not where they penetrate the fireplace walls. The untreated wood is resting on bazillion year old stone so the moisture from curing isn’t the reason for the rot. They are 8 feet off the ground so it isn’t wicking up of moisture from grade that is the reason for the rot. And no water is coming in from outside, so outside moisture isn’t the reason for the rot.
This is also seen in turn of the century city row homes where the ends of floor joists (sometimes 2 or more stories up from grade) resting on the inside row of brick on a 2 brick thick exterior wall are rotted while the ends of the floor joists resting on the interior brick walls are fine.
Where is the moisture that is causing the rot coming from and what is causing this moisture?
Interior moisture laden air condensing on the cold brick surface near the wood causes the wood to wick this moisture up and eventuallly rot.
The reason that the ends of the wood joist are still high and dry would be explained as the surroundings in this case stone, is wicking the moisture out of the wood and keeping it dry. Under 19%.
If the rest of the framing is getting rotted, would logically be explained with the water vapor transmission from the surroundings. The humidity levels in a confined area such as a crawl space or basement, will and would create premature deterioration of the wood fibers with excessive moisture.
If I could explain this in French vocally, maybe it would go faster, but you would not follow the meanings. ha. ha.
Marcel 
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The stone on the exterior walls gets moisture from outside when it rains, and the moisture is being absorbed into the mortar.
An inner wall of double brick would also not get the moisture from the exterior and will stay dry and in better shape over the years.
The interior walls will do not get the moisture from outside and does not get wet.
Michael basically got it. The reason inspectors often find rot at the point where untreated girders come in contact with walls is that most LOAD BEARING walls are also EXTERIOR walls and are therefore cold. Condensation builds up where the wall is thinest (like at a girder notch). The moisture doesn’t come from wicking (which can’t happen on a second floor) or curing (which can’t happen with stone) but from indoor air condensing on a masonry wall at the spot where the wall and the indoor air temperatures are greatest in difference.
Basically is good enough for me Nick.