Loft joists

weeg

That's not a beam - not at that size, sitting on top of the joists. Best guess is that it's a lateral bracing member. From your description, you will definitely need to strengthen what's there if you want to use it as a room. Doubling up the joists should do it, but I'd echo those who are advising professional advice.

DevilDamo

*waits in anticipation for new thread asking how to replace collapsed ceilings*

saj_chow

DevilDamo said:

*waits in anticipation for new thread asking how to replace collapsed ceilings*

Hope it doesnt come to that but there is a strong possibility of that. 

bpj

Our ceiling joists have the same approximate measurements, and they've clearly been boarded for decades. We don't use it as a hobby area, but I walk around up there plenty.

We're aware that we shouldn't store anything too heavy, but given the old cold water storage tank didn't cause any obvious problems have been pretty relaxed about it.

Most responders to this thread suggest this is a problem. Is this just an automatic response to a questionable strengthening proposal, or is the structure actually inadequate?

weeg

bpj said:

Our ceiling joists have the same approximate measurements, and they've clearly been boarded for decades. We don't use it as a hobby area, but I walk around up there plenty.

We're aware that we shouldn't store anything too heavy, but given the old cold water storage tank didn't cause any obvious problems have been pretty relaxed about it.

Most responders to this thread suggest this is a problem. Is this just an automatic response to a questionable strengthening proposal, or is the structure actually inadequate?

The structure sounds inadequate for the proposal. Those joists fall far below the sizes you'd find in a joist span/ load table. To a huge extent, it depends on the age of the house. Modern houses have trusses engineered to absolute minimum cost, with an allowance of 25kg/m2 for storage (ish). If it's a 1930s house then odds are it was done by rule of thumb, and the timbers tend to be stronger/ have dried out thoroughly meaning they deflect less. 

If you had a water storage tank up there, then the roof was designed for that load, and your storage is probably much less.

From the OPs suggested way of strengthening, it's pretty clear they aren't that knowledgeable about buildings, and it's way cheaper to pay for some professional advice than it is to pay for repairs if it goes wrong. Trust me, I have some deeply stupid things done to attics.

saj_chow

Thanks for all the advise will see how it pans out. will post results here if anyones intrested.