Attic Conversion - Too be RSJ's, or not to be RSJ's!!!

B

bobbylewis

Guest
Hi.

I’m seeking advice on an attic conversion in my home.

The house is 3 bed mid terrace, Timber frame, without a concrete gable wall between us and the neighbours on both sides. Approx dimensions of the house are 10m Deep and 5 meters wide and a max height in the attic of 3.5m.

After the conversion the habitable space will be 3.8m x 4.8m, with a 1m squared landing space.

Now, where im seeking the advice is related to the reinforcement of the roof. I’ve been getting conflicting quotes from contractors in regards to the use of RSJ’s. Some say they have to be used for reinforcement; other contractors say you can’t use steel because the house has no concrete gable walls to fix them onto, and that the roof and existing structure can be reinforced with timber. This to me makes sense, as I know RSJ’s are extremely heavy and resting them on a timber gable walls seems wrong. Reinforcing the structure with timber is definitely a bigger job so I don’t think that corners are been cut here.

I need advise.

Rob
 
bobbylewis said:
Hi.

I’m seeking advice on an attic conversion in my home.

The house is 3 bed mid terrace, Timber frame, without a concrete gable wall between us and the neighbours on both sides. Approx dimensions of the house are 10m Deep and 5 meters wide and a max height in the attic of 3.5m.

After the conversion the habitable space will be 3.8m x 4.8m, with a 1m squared landing space.

Now, where im seeking the advice is related to the reinforcement of the roof. I’ve been getting conflicting quotes from contractors in regards to the use of RSJ’s. Some say they have to be used for reinforcement; other contractors say you can’t use steel because the house has no concrete gable walls to fix them onto, and that the roof and existing structure can be reinforced with timber. This to me makes sense, as I know RSJ’s are extremely heavy and resting them on a timber gable walls seems wrong. Reinforcing the structure with timber is definitely a bigger job so I don’t think that corners are been cut here.

I need advise.

Rob
Click to expand...

the simplest advice here rob is to engage a professional...!!!!!

you have serious issues here, apart from the rsjs....

1. exactly what needs to be done to convert the roof ie are there trussess or a cut roof?? if trusses, who take sthe responsibility for altering their structural capacity?? ... certainly not the contractors..!!!!

2. you have a timber party wall... any alteration to this throws up serious fire risks... a professional would best advise as how to overcome these issues.

3. and alteration to the party wall may require permission of neighbours!!

4. if this conversion creates a third storey (ie if you already have a two storey dwelling), the fire regulations require many alterations to the existing stairwell, including self closing doors...!!! you need to know what you must include here....

5. a means of escape must be provided to the new habitable rooms which comply with fire regs...
 
Hi. Thanks for the response.

The roof is a Prefab Trussed. The contractor who I am thinking about employing has an independent engineer who will provide a compliance cert when the job is complete.

I have checked out his details along with His insurance Docs and all seem in order. The building contractor also provided me with 12 contact numbers of his last jobs, from a 12 month period. Got honest references, Good.

The contractor has assured me that the Party wall will not be interfered with, and in regards to fire, there is a new permanent staircase to be constructed for entrance/exit from the attic, along with three Velux windows in the converted space.

I’m not sure on the self closing doors!!

Feedback im getting this morning from architects are saying conversion can be done with Timber Reinforcement.
I’m doing my homework on this one as I want the job done correctly.

Any other advice much appreciated.

Rob
 
A 3 storey house has different regs and fire doors with closures are mandatory. Also if you take the closers off you will invalidate your insurance. That is why the self closing doors are specified.

As previous get an independant structural engineer to look at the dwgs. RSJ's will be cheaper than reinforced timber.
 
I agree you should employ a Structural Engineer.

Did the Architect complete a Structural Design?
Does the Architects PI (Professional Indnemity Insurance) Cover him to design structural elements?

Have issues relating to building regulations been met? E.g Part B (Fire), Part K (Stairways and Ramps).................

The cost of employing a Structural Engineer would be of the order of €800, money very well spent.
 
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