06:01PM | 02/03/05
Member Since: 02/02/05
2 lifetime posts
I am working with my father to add several bedrooms in his attic. His house was built in the 1920's, and even though it is huge, only has 2 bedrooms and one bathroom.

The attic is huge, approximately 25 feet by 45 feet with a 12 foot peak. We are concerned about load on the floors. the floors were built with 2x8's and in certain places span up to 20 feet below. The main area has a dining room 15x20 with 9' ceilings adjoined by an archway to a living room that is 20x15 with 9' ceilings. We need to beef up the floors to handle the live load without cracking the plaster in the ceilings below.

Not to mention, my father just retired, so we are on a limited budget.


11:55AM | 02/04/05
Member Since: 06/06/03
1250 lifetime posts
I am not sure exactly what your question is, but that's never stopped me from responding before!

You are wise to be concerned about floor loads. I'm no expert, but I've heard that attic conversions are a lot more intensive than most people think.

It's not only floor loading, but things like fire egress. And having the floor plan make sense when it's all done.

Your attic sounds great, however! I am envious! I wish my own home had a big bunch of unused area!

If it were me, I'd be talking to a contractor that does attic conversions. Have any of your neighbors gone through this process?


-k2 in CO

Moderator, Miscellaneous Forum


06:08PM | 02/04/05
Member Since: 02/02/05
2 lifetime posts
I don't know of any neighbors that have done similar.

We have considered options such as doubling floor joists to better support the load.

The question is: does anyone have any suggestions they can offer for a frugal budget to convert an attic set up for storage load to live load?



08:16PM | 02/04/05
Member Since: 07/01/03
558 lifetime posts
The budget is limited, but you have to meet minimum standards in finishing 100+ square feet. You are going to need at least 34 20' long joists (2x10 sistered to existing 2x8) to reinforce the floors, and a number of 2x4s to form the knee walls, door frames and partition walls. A major expense (about $2000) will be plywood or OSB sheeting for the floor. Electrical can be probably one or two circuits, insulation upgrade, and I assume finish will be drywall with minimal trim, inexpensive lighting, inexpensive floor coverings and no plumbing. You need to consider how to heat and cool this space and whether you need windows and dormers. As mentioned by K2, code requires windows large enough to serve as fire escape. Oh, and permits.

I think you need to have at least $6K in the budget, assuming you are going to do this yourself and do spartan finish work, no windows, or HVAC. If that figure gives dad sticker shock, don't bother starting, or scale back the plans to only part of the attic. Seriously, that is a rock bottom figure.

If you want to budget this, you need to draft your plans and develop a cut list of materials. It is a big enough project that you can probably bid the materials to a couple suppliers and get a builder price. Plan ahead to understand the budget up front and figure out where you can cut costs and where you might be able to splurge.


09:20PM | 02/04/05
Member Since: 01/28/03
694 lifetime posts
Beg to differ with TomH.

The load calculations for 2x8s at #2 spf lumber state that the maximum span at 16" on center is about 13'.

See here:

Even doubling (aka 'sistering') the joists may not meet minimum building code requirements for anything more than about 13 feet.

That said, it is quite impossible to meet code and do as TomH suggests in most cases.

Bottom line is that any code compliant properly load bearing floor conversion for any attic should meet minimum 40-50lb per square foot load requirement.

No offense to TomH, but until he proves by Code calcs that his suggestions will meet minimum requirements for spans and loads in this case...his advice remains all wet....


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