Post & Beam house owners

[Jay Jolliffe]

Does anyone know what the humidity should in a post & beam house. The house is about 4,000sq' & is in Maine. There is a lot of checking & shrinkage. I'm trying to find out why.

[Chuck Wintle]

How old is the house? a new one will show some shrinkage...at least at the beginning.

[Jay Jolliffe]

The house is 5 yrs old. But that's from the start of construction. So I'd say 3 yrs with any source of heat....

[Craig D Peltier]

Having lived in a newly built log home in Mass before, I remember checking happened for years.I remember having to crank down the post for about 3 years. Sometimes you would here loud crakcs years later.

[Scott T Smith]

Jay, checking and shrinkage in timber frame structures is quite common, unless the timbers were seasoned for several years prior to erection.

Usually, the drying time associated with timber frame timbers is anywhere between 5 - 10 years. Homeowners keep their RH at a level that is comfortable for them - typically in the 50% range. Often times the bulk of the shrinkage does not become obvious until the timbers are fairly dry.

Shrinkage depends upon the species, cut and thickness, but a 3/4" shrinkage on a 10" beam would not be uncommon. (8% or so).

If purchased new, the very best timbers for a timber frame would be those that were dried in an RF Vacuum kiln; however these kilns are extremely expensive (usually cost up to 500K to build one). The second option would be a standard vacuum kiln, but still is not very common.

Many timberframers try to find salvage timbers, that way all of the shrinkage has already taken place.

[Kenneth Moar]

The Timberframe section of The Forestry Forum might get you more information. But I can't resist this one, you must be messing with us and you hooked me. The simple answer to why there is checking and shrinkage is that your house is built of wood. You didn't mention if your timbers were fresh cut , kiln dried or decades old, but some timberframe or post and beam homes are built with lumber that was cut the day before it was used in the building. Regardless, unless the wood is already at an equilibrum MC of about 7-9% at the time the structure is closed in, it will begin to dry out and being wood it checks and shrinks.
Not to worry tho checking in timbers is normal , and doesn't typically affect structural integrity, provided the timbers are sized properly for the loads they must carry. Shrinkage also is normal and is managed by proper joinery and construction techniques. So sit back and relax, if you are heating the interior to say 20 deg C 68 deg F , with proper ventilation you will achieve an indoor relative humidity around 45% and your timbers will eventually reach an equilibrum MC of about 9% in winter , and slightly increasing during humid summer weather. You could humidify your interior, but I doubt you would notice any signifigant difference. If the house is properly constructed sit back and enjoy the natural beauty of the timbers checks and all.

[Bill Davis]

Shrinkage and checking more likely depends on the average RH in your location and the initial MC of the logs.

If your avg RH is not nearly equal to the equilibrium relative hymidity of the wood shrinking or swelling of the wood will occur and that causes checking and splitting.

[Jay Jolliffe]

Normal or not normal checking & shrinkage ?......If someone would tell me how to do pic so their easy to see I'd appreciate it

[Chuck Wintle]

Normal or not normal checking & shrinkage ?......If someone would tell me how to do pic so their easy to see I'd appreciate it

Are the beams Oak?

[Jay Jolliffe]

The beams are red oak

[Scott T Smith]

Jay, I have seen oak look like this when large beams were dried too quickly. If I had to guess, I would judge that regarding the beam in the first photo, the side with the most extensive checking was closest to the pith.

I have several thousand board feet of oak timber frame beams in storage that I had milled back in 2002, and some exhibit checking that is similar to yours. Others are fine.

I would also hazard a guess that the beams with the worst checks came from fairly fast growing trees, and that the growth rings were not spaced very closely together.

I believe that some of the gaps in the joinery could have been minimized had different techniques been used when designing and milling the various joints.

To minimize checking when using oak beams, fell and mill them in the fall and stack/sticker in a cool, dark place with minimal wind. Either box the heart or make sure that no beam has pithwood along the edge. They would need to air dry for several years before use.

Structurally, they should be fine.

[Chuck Wintle]

The beams are red oak

could some of the splits be drawn together with clamps and glued?

[Jay Jolliffe]

I don't think clamps & glue would work in this case Chuck. Have you ever tried to clamp a crack closed on a 10"thick beam....
Scott ....From what I understand the red oak was cut,milled & put up after only 2 months of cutting the trees down.

[Bill Edwards(2)]

I don't think clamps & glue would work in this case Chuck. Have you ever tried to clamp a crack closed on a 10"thick beam....
Scott ....From what I understand the red oak was cut,milled & put up after only 2 months of cutting the trees down.

Pipe clamp will produce a lot of pressure.

I pullled a 16' framing span to plum with one.

[Chuck Wintle]

I don't think clamps & glue would work in this case Chuck. Have you ever tried to clamp a crack closed on a 10"thick beam....
Scott ....From what I understand the red oak was cut,milled & put up after only 2 months of cutting the trees down.

No I have never tried to do that.

[Kenneth Moar]

Hey Jay, those are some interesting photos. Now I understand your concerns. Aesthetically , they appear quite dramatic, I hope those are the worst examples. I'm guessing the effect is
more eye catching in the close-up shots, When viewing the particular joints in the context of the larger frame is it less eye catching?
Anyways, beyond aesthetics, structural integrity would be my concern. I'm not suggesting anything based on those photos, just saying, and wondering where is the builder and what
has he said. Red oak is one of those species that can be pretty lively as it dries and shrinks and you are seeing the results of that for sure. Large checks in large timbers are pretty standard and are part of the timber frame aesthetic for many NA species.
You mentioned the timbers were basically "green" when the frame went up, so when the building was enclosed and the air "conditioned" the shrinkage would accelerate and the majority of shrinkage in red oak occurs as the MC reduces from about 20% down to equilibrium MC of 7-8% . You could humidify your indoor space to around 60% which would slow shrinkage
if the MC is still above 14%. One thing you could do is beg borrow or steal a good quality pinless moisture meter and verify the actual MC of the timbers. If the average MC is close to equilibrium then there is not much use messing with the interior RH. As I mentioned in my previous post, try the Forestry Forum, or the Timber Framers Guild, I'm sure ther would be info
a plenty to be had on those forums.

BstRgds
Ken

[Jay Jolliffe]

After reading my answer Chuck, it sounds like I was trying to be a wise a** I really wasn't. That's a lot of wood to try to pull together with clamps.

[Chuck Wintle]

After reading my answer Chuck, it sounds like I was trying to be a wise a** I really wasn't. That's a lot of wood to try to pull together with clamps.

Jay,
no offense..i did not take it a wise a** answer.

[John Keeton]

Jay, our timberframe home is red oak, and, as is often the case, constructed on green timbers. It has cracked quite a bit, and there is some substantial shrinkage - all of which we anticipated. However, the joinery in the pics you posted seems unusual to me, and we have not experienced that type of movement. Only our great hall (28' x 44') is framed, and it is done with hammerbeam bents. The frame was designed to absorb the shrinkage toward the outside which actually tightened the frame as it dried.