Has anyone used PT lumber for a house’s main beam?
I’m in the process of changing out a water/termite damaged 49′ beam. Bugman says the termites have been treated long ago and are gone, but I’m paranoid. I’d been planning on using steel until I got the $1k price tag.
PT would be around $300 and is SUPPOSED to be disliked by termites and other wood eating bugs.
jt8
“Politics is supposed to be the second oldest profession. I have come to realize that it bears a very close resemblance to the first.”
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The main problem I would see in using pressure treated for a beam is finding dry enough material. Shrinkage rates for a 2x12 pt. are substantial, and when a main beam shrinks it lets your floor joists drop by the amount of shrinkage, which could be in the range of 1/2" or more. Joists at exterior walls however stay at the same elevation, causing all kinds of problems. I'm not sure about LVL's resistance to bugs, but that's all we use for main beams anymore. I would think with the glues and waxes used in them they might hold up allright but it's worth checking out.
The main problem I would see in using pressure treated for a beam is finding dry enough material. Shrinkage rates for a 2x12 pt. are substantial, and when a main beam shrinks it lets your floor joists drop by the amount of shrinkage,
That was the reason I'd knocked it off the list initially and was looking at steel.
Only way I can see around the shrinkage issue would be to go down there and re-shim it every couple months for a year or so. Sounds like a PITA.
But does that mean I'm stuck paying for the steel? $1k for just the beam and joining plates. And since I've never done steel, I'm fuzzy on how it integrates with the joists, posts, et al. In some cases I've seen where they've bolted wood to the steel and then nail the joists into that. Or can the joists just sit on top of the I-beam?
This is a point where I'd typically bring in a pro to do the job, but the first estimate I got was $5-8k, and the budget can't handle that hit just for the beam.jt8
"Do not let what you cannot do interfere with what you can do."-- John R. Wooden
How big is your hurry? Could you store the PT in the crawl for say, 6 months?Andy Engel
Never try to teach a pig to sing. It wastes your time and annoys the pig.
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None of this matters in geological time.
How big is your hurry? Could you store the PT in the crawl for say, 6 months?
No. The clock is running and the beam is holding up the show. Since this project house wasn't in move-in condition, I picked it up with a commercial loan. I'd like to be able to convert that to a mortgage in less than 6 months (move into it). Once I'm moved in, I can take my time to do the finish work. And then start looking for the next one.
I usually avoid houses with big structural issues, but the location was good enough that I jumped on it.
[edit] Plus, my termite paranoia would like to see that old beam out in the dumpster with me taking it apart to make sure there really isn't anything alive in it.
jt8
"Do not let what you cannot do interfere with what you can do."-- John R. Wooden
Edited 11/22/2005 3:32 pm by JohnT8
You could pre-camber the beam. In other words, when you install the beam, install additional shimming to raise the beam (say 3/8"). When the beam dries and shrinks, it will become level.
this scenario would create havoc with drywall cracks and interior doors binding
John, do the PT and do the shims. My gut says you personally will be happier in the long run that way.Once the beam is set, spray everything down with a mixture of anti-freeze, borax, and boric acid. Use a garden sprayer. Get it all good and wet. Paint the ends of the beam before you set it, with the same mixture. Paint those ends several times, and let it dry in between times.Now keep your pets out of the crawlspace long enough for everything to dry. The anti-freeze being the only concern there. And the borax and boric acid should make that bitter enough that it really shouldn't be a problem anyway.That beam will never get et by termites, mold, rot, fungus, etc...
America is a country which produces citizens who will cross the ocean to fight for democracy but won't cross the street to vote.
spray everything down with a mixture of anti-freeze, borax, and boric acid. Use a garden sprayer.
Do you have a recipe for your cocktail?jt8
"Do not let what you cannot do interfere with what you can do."-- John R. Wooden
Not positive, but I believe the recipe was 1 cup each of the borax and boric acid, to one gallon of anti-freeze.Then dilute that mixture enough to spray it from a pump-up type garden sprayer.Probably easier to dilute the solids before adding to the anti-freeze. Yer going to dilute the final mixture anyway. Use hot water to dilute the solids.And Jeff Buck is right. Spray everything down prior to installing the new beam, as well.Ventilate the crawlspace well, while you are spraying, and while it dries. It's a good thing that you will have part of the floor ripped up during the process. That's a good time to spray, before you put the flooring back down. As far as danger using this stuff... From what I read, you'd basically have to drink the stuff to poison yourself with it. You can wear a respirator while spraying, if you want, but you'd almost have to continuously spray yourself in the face with it, to do any damage.After it dries, you'd have to lick the entire beam rather lavishly to get enough into your system to make you sick...From what I read, just plain old anti-freeze alone stopped rot, mold, mildew, and fungus.BTW: pt inside, as opposed to only for "sill plates"... Since when is that beam any more "inside" than the sill plates are ?
America is a country which produces citizens who will cross the ocean to fight for democracy but won't cross the street to vote.
Actually the 2000 international residential code calls for PT beams if they are closer than 12" to the ground.
Section R323 Protection against decay.....the following locations shall require the use of an approved species and grade of lumber, pressure preservatively treated in accordance with blah,blah,blah..., or decay-resistant heartwood of redwood, black locust, or cedars.
1.Wood joists... closer than 18 inches or wood girders when closer than 12 inches to exposed ground in crawl spaces .....blah,blah,blah...
inspector mite not allow pt in the house soak ends of conventional framing lumber w something like thompson waterseal or pheno? line beam pocket, if one, w ice/water shield?
John,
Why don't you just wrap the beam before you put it in with copper flashing, snow/ice shield or vycor or something and use a regular beam.
I would look for lumber that has been kiln dried after treatment (kdat). It will already be somewhat pre-shrunk and much lighter to handle. In my area it is readily available at about the same price as air-dry acq.
Edited 11/22/2005 6:10 pm ET by rdnolte1
what's the cost on bug-proofing regular framing lumber from the get go?
spray the hell outta the beam pocket ... wrap the beam in bug-proof materials as suggested ... then get it all sprayed just because yer U.
I run into bug problems all the time on old houses ... just address the moisture issues, demo the rotten, and get the old sprayed before the new coveres it all back up.
No reason your wood beam can't be treated, as in bug treated.
Jeff
Buck Construction
Artistry In Carpentry
Pittsburgh Pa
John, if you use PT you'll save $1000. You'll have to go down there and re-shim twice. It will take ten minutes each time. So, you'll be "wasting" twenty minutes of your life.
Where else can you make $1000 in 20 minutes?
Oh! That doesn't factor in the 20 hour savings you'll have gain by using lumber!
blue
Definetely use the PT.
More than likely you will be able to find enough pieces that are reasonably dry. Use adjustable columns and raise as needed.
If the situation is so bad that you must go to great lengths to protect the beam I would correct the situation before guarding against symptoms. Even if you did use steel you would be susceptible to termite damage in your rim joists, joists ends, sheathing, plates, and studs.
Do whatever you have to do (treating, grading, shields) to ensure the insects are not even close to the beam or any important elements.
Jon Blakemore
RappahannockINC.com Fredericksburg, VA
Borax treated lumber. I know I can get 2x4 & 2x6 here, youi might check into it.
Borax treated lumber. I know I can get 2x4 & 2x6 here, youi might check into it.
Is that a variation on PT? I was planning on looking for some borax treated EPS, XPS to replace the Dow blue board down there now.jt8
"Do not let what you cannot do interfere with what you can do."-- John R. Wooden
There might be a bit of info about the borax wood at http://www.borax.com/wood/ , but I didn't check it too much. My vote would be to just go with the PT, and re-shim it later on.
I think it was said already, but double check with your building dept. about using PT. My town does not allow it inside the house - only for sill plates.
Thanks for all your suggestions. Don't see anyone really saying spend the extra $$ for steel, so looks like the first option would be to try to locate kiln dried PT locally. I hadn't even realized that such a product was available. All the PT I've bought in the past was anywhere from damp to nearly dripping.
Was going to use tarpaper on the beam pockets, but the snow/ice shield might serve better.
The house is located in a small town. When I went into the villiage office to ask about codes and inspections, the lady said, "well, if you're going to put on an addition, we'll send out Mr. So-and-so to take a look at your site, but otherwise..." So I don't think I'll have to worry about an inspector crawling around down there pooh-poohing the PT. I would be using the engineer's recommendations on dimensions (he just didn't make provision for bug-proof..not really his bailiwick).
jt8
"Do not let what you cannot do interfere with what you can do."-- John R. Wooden
John,
Have you considered using treated lvl's? Check with your lumber company on availability. You won't have the worry of dimensional stability, I'm not sure on the price difference vs. steel, but have used these on exterior decks, etc.
John, you can get paralams pressure treated too. Also, some pressure treatments reduce the strength of the lumber. Make sure you size your beam and spans properly.
Woodroe
IIRC, I thought insects only ate wet or rotting wood... not healthy stuff. if the beam is esposed in a dry basement, you may not have to worry.
The difference between stupidity and genius is that genius has its limits. -Albert Einstein
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IIRC, I thought insects only ate wet or rotting wood... not healthy stuff. if the beam is esposed in a dry basement, you may not have to worry.
I think one variety of termite goes for decaying wood. But IIRC, they aren't all that picky. And while pulling drywall, I found trails that led all the way to the first floor ceiling (haven't demo'ed the attic yet).
But yeah, it was worse in areas that got damp, like the crawlspace.
jt8
"Do not let what you cannot do interfere with what you can do."-- John R. Wooden
Also, some pressure treatments reduce the strength of the lumber. Make sure you size your beam and spans properly.
My guy at the lumber yard was concerned that PT was a lower grade than kiln dried and therefore might not be as good, but I'm not too concerned about that. With 3 concrete block posts and 4 jack posts in a 49' span, none of the spans are over 5-7'.
jt8
"Do not let what you cannot do interfere with what you can do."-- John R. Wooden
If you do use wood, consider steel shims. We use them a lot in renovation work to level floor systems up. 2 shims driven from opposite sides over lapping one another, like setting a door jamb. They won't break or compress over the weeks of incremental driving and lifting. Usually when you take your time, the plaster doesn't even crack.
If you do use wood, consider steel shims. We use them a lot in renovation work to level floor systems up. 2 shims driven from opposite sides over lapping one another, like setting a door jamb.
Does the lumber yard typically carry them?
Usually when you take your time, the plaster doesn't even crack
Probably not a real issue right now. :)
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jt8
"Do not let what you cannot do interfere with what you can do."-- John R. Wooden
Edited 11/24/2005 11:10 pm by JohnT8
But you might rack those door frames !!!!!
But you might rack those door frames !!!!!
We have the first span done. Closet door on BR3 now closes!!!
For a brief moment, thought I'd located some pt oak I could use. But it was a seasonal item and they were out of stock until Spring. Couldn't find dried pt syp, so bought regular and stacked them up for a couple weeks of drying. More for my own amusement than anything, since they would need months to air dry.
Attached updated pics of the first segment removal (lovely looking old beam) and the pt new first segment beam (3 2x10s as per engineer). Haven't put the new jack post in yet to split the span.
On the bottle jacks... I called around at the rental places for 10 ton jacks. One place had 4 matching 20 tons, but wanted $20/ea per day. At $80/day, I said 'screw it, I'll go buy some' (said it to myself, not the rental guy). Lowes had Kobalt 12 tons for $24.xx ea. Picked up 4 of them. That is WAAAy overkill for what I'm lifting, but I'd rather have overkill than underkill.
We're lifting 16' sections and putting in 11-13.5' beam segments. Those are the spans between concrete block pillars. 2 non-pt 2x10x16' screwed together on either side of the beam as jacking-beams. 4x6 as temp vertical posts.
Hope to get the remaining 3 segments done this week. Need to move some wiring and ductwork to get to the second segment.jt8
"The cynic is one who knows the price of everything and the value of nothing." --Oscar Wilde
In almost all cases in our area we use structural steel in the basement and other high load areas, so our structural supplier supplies the shims. I doubt if a lumber yard would carry them. I learned this trick from a structural engineer many moons agoNever serious, but always right.