I wonder how much a wall stud can expand in length. When I built the floor framework, I used a crosspiece between two fixed floor joists. Usually, I cut studs a few millimeters short, but this time I got it just right that I needed to use a hammer to get it in place. Now, afterwards, I'm wondering if it's appropriate to have it so "tight". Does anyone have knowledge about this?
/Tigersågen
/Tigersågen
Member
· Korpilombolo
· 3 610 posts
It doesn't become longer than when the timber was fresh. The length change for wood is marginal and on a short(!) log it should be completely negligible.
Most people I know, including myself and two carpenters, usually cut the studs a few millimeters too long as it's much easier to install them that way: Tap them into place and toenail/screw - much easier when the stud doesn't move around. Timber doesn't grow in length over time.
I thought about wooden floors that have the ability to expand in humid weather and shrink in dry weather. I've heard that floors laid too "tight" can essentially explode walls. Usually, wood can expand in a certain direction, but in my case, it can't, which would mean a wall would explode 
.
But I interpret your responses to mean I don't need to worry and can lay down chipboard, leveling compound, waterproofing layer, and tiles without the floor and walls exploding.
Tigersågen
.But I interpret your responses to mean I don't need to worry and can lay down chipboard, leveling compound, waterproofing layer, and tiles without the floor and walls exploding
.Tigersågen
However, the floor might rise... some walls won't explode...
I mean if you install floating floors like parquet, etc...
I mean if you install floating floors like parquet, etc...
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a floor surface is as you say but a kortling doesn't do it all. or maybe a fraction of a mm. calculate how big a kortling is vs an entire floor and you'll understand that they the floor needs 5mm clearance at the skirting boards, so the kortling probably doesn't need any clearance at all
Yes, but the main point is not that a kortling is smaller than a floor, but that if wood swells due to moisture absorption, it does so primarily in the width, i.e., across the grain direction - the expansion in length, as Benno says, is negligible.
Diversearbetare
· Göteborg
· 10 713 posts
A plank floor moves in only one direction, i.e., across.
Thank you to everyone who responded, now I can sleep peacefully at night .
Best regards/Tigersågen
.Best regards/Tigersågen
Wood actually moves due to changes in both moisture content and temperature. Pine has a linear expansion coefficient of 5 * 10^-6 parallel to the fibers and 30 * 10^-6 perpendicular to the fibers due to temperature changes.
Its moisture movement is greatest in the tangential direction to the growth rings and about 50% of this value in the radial direction. The axial moisture movement is indeed much smaller but can still be measured—about 10% of the tangential. Typical values for a certain piece of pine might be
8% tangential
4% radial
1% axial
1% may seem very little, but it corresponds to 1cm per meter. Thus, there can be significant movement even along a long board or plank.
Its moisture movement is greatest in the tangential direction to the growth rings and about 50% of this value in the radial direction. The axial moisture movement is indeed much smaller but can still be measured—about 10% of the tangential. Typical values for a certain piece of pine might be
8% tangential
4% radial
1% axial
1% may seem very little, but it corresponds to 1cm per meter. Thus, there can be significant movement even along a long board or plank.
But in practice, any potential length development does not matter at all. Of course, as BobbyEwing says, you cut them a few mm too long and fasten the studs with the help of a hammer and skew nails afterward. Wobbling around with too short noggings or studs is really a lousy job that requires twice as many hands as you have and just causes trouble.
The other day, I built a partition between two rooms with the idea that you should be able to take down the wall and make one large room once the children are grown and no longer need the bedrooms. Therefore, the parquet was laid under the wall, and you don't want nail holes there. The bottom stud was laid with foam underneath as protection and skew-nailed to the wall, and the corresponding ceiling stud was fastened with three nails in the ceiling as well as skew nails to the wall. Then we secured the "Too long" studs that were skew-nailed in place. It became rock solid, and once the OSB + gypsum is in place, I promise it is firmly set. Any length development in this case only makes the wall more stable. Not that it's needed, but... I can't see any problem with this.
The other day, I built a partition between two rooms with the idea that you should be able to take down the wall and make one large room once the children are grown and no longer need the bedrooms. Therefore, the parquet was laid under the wall, and you don't want nail holes there. The bottom stud was laid with foam underneath as protection and skew-nailed to the wall, and the corresponding ceiling stud was fastened with three nails in the ceiling as well as skew nails to the wall. Then we secured the "Too long" studs that were skew-nailed in place. It became rock solid, and once the OSB + gypsum is in place, I promise it is firmly set. Any length development in this case only makes the wall more stable. Not that it's needed, but... I can't see any problem with this.
I'm not entirely sure I understand you. But what change in moisture content and temperature do you mean is required for a pine beam to change 1% in length? Offhand, it sounds like a very large change. Such length differences don't even occur in decking that has gone from soaking wet to very dried out after several years outside and 3 weeks of summer heat.anaitis said:
MOISTUREDaniel_N said:
I don't have my reference literature available now, but I seem to recall that the moisture movements apply if the moisture content goes from fiber saturation (about 28%) to furniture dry (about 12%). This is from memory, though.
This is probably quite MEASURABLE even on pressure-treated wood. The naked eye might not be precise enough.
TEMPERATURE
If we consider a 40-degree temperature difference (warm spring day in the sun - cold night), we get along the fiber direction
40 * 5 * 10^-6= 200 * 10^-6 = 0.2 * 10^-3= 0.02% or 0.2 mm per m.
So, quite little compared to moisture movement!
In the other direction, it would be 6 times as much.
Hope I calculated correctly now!!
According to this page, the length movements are only 0.01% per percentage point of moisture content, not 0.06%, as shown in anaitis example.
Furthermore, there aren't particularly large variations in moisture content in the timber in a house. This is not an important factor, but perhaps everyone agrees on that.
Furthermore, there aren't particularly large variations in moisture content in the timber in a house. This is not an important factor, but perhaps everyone agrees on that.