Hi guys.
First, I’d like to thank all of you for your great advice, I’m in the planning stages of a basement remodel and have spent many hours so far searching through past posts for structural information regarding recessing a main beam to gain headroom.
My house is a 1968 rancher (single story) with a somewhat shallow basement that I’d like to finish off as a rec room. Because the floor Joists are only 82 Inches off the floor, headroom is a real problem. The area of the basement that I want to renovate is appx 26′ x 22′ with the main beam (3 – 2×10’s parallel with the roof peak) running a foot off center down the 22′ length and a column in the middle and each end of the span. The floor joists are also 2×10’s sitting on top of the main beam.
If I could have everything I would like to recess the beam and hang the floor joists off the side of the beam using joist hangers AND get rid of the center column. Based on what I’ve learned so far, a 22′ span may require a beam taller than my floor joists. If that where the case I would settle for keeping the center post and keep my headroom.
It looks like an I-beam may be a solution for the span or maybe an LVL – I’m not sure. My plan is to draw up the details and have an engineer tweak/approve them. Don’t worry, I wouldn’t attempt this without an engineer’s approval, but never having done a project like this, I’d like to know if anything I’m planning to do is just crazy or if it’s a common issue with a pretty standard solution.
I understand the process of replacing the beam – tight stud walls on either side, trim down the floor joists etc…. I’m just not sure of the correct material and I’d like objective opinions so I can make an informed decision.
Replies
With a 22' span beam, you're looking at an LVL 18" deep or more. So a steel beam might be your best bet.
You can fill the sides of the steel beam with wood and hang the floor joists off that.
But even with steel, you're probably looking at a 12" deep beam.
Thanks for the info Boss,
Is there a rule of thumb you use to figure that out? Do you know of any resources for the structural capabilities of steel I-beams?
"Is there a rule of thumb you use to figure that out? "
Yup. With wood beams, you figure an inch of depth for every foot of beam span. That's not a definite rule - Just a starting point. If you exeed that by a lot, you're likely to need a lot of plies or else the beam just won't work.
Steel will go more like 15-to-1 on spans.
"Do you know of any resources for the structural capabilities of steel I-beams?"
No, and I wouldn't pass them along if I did. The most important thing in beam design isn't figuring out the beam - It's figuring out what the beam carries. That's not always simple.
Military justice is to justice what military music is to music.
In addition to the floor joists sitting on the beam, that beam may well be carrying the load-bearing walls and roof loads from above. You may have to do more than support the first floor when you remove the beam.
Al Mollitor, Sharon MA
There is a wall sitting directly above the beam that supports the ceiling joists and the roof is 2x6 rafters with a collar tie and a verticle 2x4 every 6th rafter. The 2x4's sit on the ceiling joists about a foot away from the wall below.
Should I also add temp supports on the main floor to support the ceiling? Sounds like I should.
OK, so when does someone suggest renting the jackhammer and lowering the basement? ;)
Hadn't thought of that, but now that you mention it, the sewer pipes are under there. If it's not one thing it's another. Maybe I'll just leave it a workshop.
yes, these messages can be very creative. Helpful? LOL.
NO, I love the these messages adn all the suggestions. But, jack hammers?
yes, these messages can be very creative. Helpful? LOL.
NO, I love the these messages adn all the suggestions. But, jack hammers?
We're just not pulling in the BT diggers. There are BT'ers who have 'lowered' basements. To me it sounds like a major PITA. Getting the old crete out and where's the footing going to wind up if you lower the floor a couple feet? And how are you going to support the whole sheebang while excavating...etc. And as the original poster mentioned, how about the sewer lines?
Or the other group who jack the house up a couple feet and then add to the foundation walls. Which has its own collection of challenges.
Either way, it can turn into an expensive nightmare in a hurry. jt8
I've seen a couple of crappy examples of lowering the basement (in 1920-era homes) where there was a "bench" along the edge where the footing was. But these lowering jobs were probably done about 1950, so you can't really blame the current generation of hacks.(In defense of the 1950ish hacks, though, the original basements had maybe 6 feet of clearance under the joists, and obviously less where ducts and pipes were. The lowering job actually made the basement accessible and usable for something other than utility access.)
Draw it up as it exists now, including info on the floors above and the roof structure, and give that to the engineer. He'll probably want to look at it himself before any final design, but the drawings can give him a starting point and allow him to do some estimates fairly quickly.
He should be able to give you the options for wood/LVL/steel in terms of beam height, posts, etc, and a rough cost estimate for the beam.
Don't forget that you have to make provision for getting the beam in there.
I just did a double lvl beam to support a roof and it was set in the attic between the ceiling joists so you dont see it from below, but maybe you could get 2 or 3 nailed together to get the support you need. Nail them together in place so that way you can get them in a lot easier 1 by 1 and they also bend a little around corners. Goodluck and dont give up