Mobile home floor sag beam size?

Shop deals on ebay
Advertise with us
SpartanEpoxies
House Repair Talk

Help Support House Repair Talk:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
U

UlyssesSign

Active Member
Joined
Jul 27, 2016
Messages
30
Reaction score
3
Hello all.
I have a mobile home that has been put on a foundation, the floor joists are 2x8 and cannot take the weight of the 14' span of the house. They are sagging considerably, I've noticed some interior walls pulling away from the ceiling by about 1/2"

I have a 5' crawlspace and plan on installing a beam under the house to take the weight.
The span of the floor is 14'.
2x8 floor joists.
I am wondering what size lumber I can get away with for the beam
I live in Canada so a 16' 2x10 is 30$. Just for reference.

Thanks guys.
 
Was the steel trailer frame removed when you put it on a foundation? 2x8 is really undersized for a 14' span. You're going to need a beam with several posts down the middle of the floor. I'm not an engineer and don't play one on TV, but I suspect a glue-lam or 3 2x10's glued and bolted together with a pier or steel post down to a footing every 8 feet.
 
Sparky617 said:
Was the steel trailer frame removed when you put it on a foundation? 2x8 is really undersized for a 14' span. You're going to need a beam with several posts down the middle of the floor. I'm not an engineer and don't play one on TV, but I suspect a glue-lam or 3 2x10's glued and bolted together with a pier or steel post down to a footing every 8 feet.
Click to expand...
A little over kill, 3 3" nails 16 inch on center, there are no forces pulling them apart.
If you can get down to the footing on the end a treated 6x6 would sit right on that. The pad in the middle would be about 24 x24" can be just dug down, no forms needed with a 3 x3 grid of 5/8 rebar keep the rebar well within the concrete.
 
unfortunately the frame was removed and discarded.
2x10's was my first plan but i was hoping to get away with 2x8's just for cost sakes, but im thinking that i will just end up saving the costs in less support jacks.
8' span would be the best even with a glue lam beam you think?
thanks,
 
the guy that did the work left a TON of cinder blocks under the house, so my plan was the just build up two end pillars to hold the beam and then jack posts for everything in between.
 
nealtw said:
A little over kill, 3 3" nails 16 inch on center, there are no forces pulling them apart.
If you can get down to the footing on the end a treated 6x6 would sit right on that. The pad in the middle would be about 24 x24" can be just dug down, no forms needed with a 3 x3 grid of 5/8 rebar keep the rebar well within the concrete.
Click to expand...


I'm not following your design there. Are you talking about a nailing pattern for the beam? Clearly, the 2x8's were designed to sit on the steel tow frame of the trailer, without that in place something structural is going to have to be added to handle the load of the floor and any load bearing walls in the trailer.
 
Sparky617 said:
I'm not following your design there. Are you talking about a nailing pattern for the beam? Clearly, the 2x8's were designed to sit on the steel tow frame of the trailer, without that in place something structural is going to have to be added to handle the load of the floor and any load bearing walls in the trailer.
Click to expand...

I was a little confused as well.
 
Seldom has an engineer ever asked for more than 3 nails 16" on center and never glue for laminating timber into a beam'
As suggested 3 ply but the span for that is too much, so a center post is needed too. posts are 6x6
The confusing part is??
 
My beam would run lengthwise on the structure, with posts every 8'. That would reduce the span of the 2x8's to 7 feet. Are you saying that span is too much and it would take two beams running lengthwise?

Bolting it together may be over-kill. See my comment about my engineering credentials or lack thereof.
 
Sparky617 said:
My beam would run lengthwise on the structure, with posts every 8'. That would reduce the span of the 2x8's to 7 feet. Are you saying that span is too much and it would take two beams running lengthwise?

Bolting it together may be over-kill. See my comment about my engineering credentials or lack thereof.
Click to expand...
My beam runs just like yours, up the middle, the ends can be posted down to the footing, I said center post but I agree with your 8 ft between posts:thbup:
 
This might help; ALLOWABLE SPANS FOR DF #2 FLOOR GIRDERS SUPPORTING ONE FLOOR ONLY
Max. Floor Dead Load: 15 psf 1, 2 (T-R602.7(2))
SIZE
20-ft Building Width 28-ft Building Width 36-ft Building Width
2-2x6- 4’- 6”- 3’- 11”- 3’- 6”
2-2x8 5’- 9” 5’- 0” 4’- 5"
2-2x10 7’- 0” 6’- 1” 5’- 5”
2-2x12 8’- 1” 7’- 0” 6’- 3”
3-2x8 7’- 2” 6’- 3” 5’- 7”
3-2x10 8’- 9” 7’- 7” 6’-9”
3-2x12 10’- 2” 8’-10” 7-10”

Transform the "width", in this case to "length".
 
Last edited:
  • Like
Reactions: K_M
Snoonyb said:
This might help; ALLOWABLE SPANS FOR DF #2 FLOOR GIRDERS SUPPORTING ONE FLOOR ONLY
Max. Floor Dead Load: 15 psf 1, 2 (T-R602.7(2))
SIZE
20-ft Building Width 28-ft Building Width 36-ft Building Width
2-2x6- 4’- 6”- 3’- 11”- 3’- 6”
2-2x8 5’- 9” 5’- 0” 4’- 5"
2-2x10 7’- 0” 6’- 1” 5’- 5”
2-2x12 8’- 1” 7’- 0” 6’- 3”
3-2x8 7’- 2” 6’- 3” 5’- 7”
3-2x10 8’- 9” 7’- 7” 6’-9”
3-2x12 10’- 2” 8’-10” 7-10”

Transform the "width", in this case to "length".
Click to expand...

and keep in mind that this is for girders (beams).

Floor joists can span much more than this.

Current building code prescriptively calls out max span for 2x8 joists:
Doug fir/larch #1 = 12'- 4"
Hem Fir #1 = 11'-10"

a 14' span *should* be a 2x10.

Also, I believe a mobile home with a removable frame is actually called a "modular home" and is designed to have the transporting structure removed once it is placed on site.
 
Last edited:
Not sure this is a modular or a mobile home. The OP called it a mobile home. Most modular homes are minimally a double-wide unit and not a single 14' wide unit.

Regardless, 2x8's are too small for the floor joist without a beam. Single wide units aren't designed to be removed from the steel trailer base. His sag issues are showing that to be the case.
 
nealtw said:
Seldom has an engineer ever asked for more than 3 nails 16" on center and never glue for laminating timber into a beam'
As suggested 3 ply but the span for that is too much, so a center post is needed too. posts are 6x6
The confusing part is??
Click to expand...

Never glue a lam beam? Am I reading this right? Why would this be?
 
Sparky617 said:
Not sure this is a modular or a mobile home. The OP called it a mobile home. Most modular homes are minimally a double-wide unit and not a single 14' wide unit.

Regardless, 2x8's are too small for the floor joist without a beam. Single wide units aren't designed to be removed from the steel trailer base. His sag issues are showing that to be the case.
Click to expand...

From sifting through the replys I should be able to go 3x2x10 lam beam.
Could I squeeze 10' spans?
 
UlyssesSign said:
From sifting through the replys I should be able to go 3x2x10 lam beam.
Could I squeeze 10' spans?
Click to expand...
Your pushing your luck but you are just taking the bounce and sag out of the floor. Make sure the crown of all 2x10s are up in the center. Most all will have a slight curve or crown.
 
nealtw said:
Your pushing your luck but you are just taking the bounce and sag out of the floor. Make sure the crown of all 2x10s are up in the center. Most all will have a slight curve or crown.
Click to expand...

This was my thought when it came to the beam. It's only really supporting a 7' span I didn't think I would have to go too crazy.
Honestly I thought 2x8s would do it, I thought wrong.
 
You must log in or register to reply here.

Latest posts

Back
Top