correct way to strengthen ceiling / floor joists?

[snowman13]

Hi Guys.

I've decided to let out the upper part of the business premises, to an office type business but upon inspection I noticed a small bounce in the floor joists.

I'm expecting an average of 12 people on the top floor at anytime.

Initially the building was designed to for residential accommodation, but recently converted for business use.

I've decided to double up on the 7x3" 16ft long joists, by adding 7x2" wooden joists.

I don't want to knock holes into the rear walls, unless you guys suggest otherwise, so I've decided to use joist hangers instead.

I understand the side concerning TownHall approval for business use, which I'll get done once I've fixed this dilemma.

Any suggestions or advice will be welcomed.

Thank you.

(the last three beams are coming out as I'll be installing stairs to go up)

Untitled

• snowman13
• 10 Oct 2013
• 2

Untitled

• snowman13
• 10 Oct 2013
• 2

 

[tony1851]

Domestic floors must be capable of supporting a load of 1.5 kN/sq.m. (about 30 lbs/sq ft).
Office loading is 2.5kN/sq.m (50lbs/sq ft).
With 7" deep joists on a 16 ft span, you will be struggling to support that load without excessive deflection/bounce.
Even if you could live with that, the local Building Control dept will insist on a floor capable of taking office loading. You really need to engage a SE.

 

[snowman13]

Domestic floors must be capable of supporting a load of 1.5 kN/sq.m. (about 30 lbs/sq ft).
Office loading is 2.5kN/sq.m (50lbs/sq ft).
With 7" deep joists on a 16 ft span, you will be struggling to support that load without excessive deflection/bounce.
Even if you could live with that, the local Building Control dept will insist on a floor capable of taking office loading. You really need to engage a SE.

hummm....

Ideally I could do with wider joists, or even better metal girders.

I guess I would be better leasing out the lower portion to a business, and the upper for private residents.

Pondering as I type......