loft conversion steel beam locations

[rico_suave]

If the lower purlin is supported beneath and I have a stud wall at the top of the stairs supporting part of the ridge beam along with collars across the length. Can the upper purlin be removed ? Will the structure be ok ?

Also is the use of steels absolutely necessary ? or would a timber floor construction be strong enough.

 

[tony1851]

The upper purlin is there for a reason; if it is removed, it is likely the rafters will deflect excessively, regardless of how well you try and restrain them with collars near the top.

Whether or not steels are required in the floor depends on the spans involved. I generally try to use timber binders, but in many cases it is just not possible.

Are you doing this as a job for someone, or is it your own loft? The main issue with lofts is the structure and, as already advised, you need to get an SE involved sooner rather than later.

 

[tony1851]

Looking at your pics again; is the first pic one of the party wall? If so, it looks like a conventional 9" brick wall (not 'single-skin) because it seems to have lots of 'headers' in it. In that case, you can support your beams off the party wall by just supporting them on your half. If the beams just have 100 bearing - that will be fine - they dont have to go on the full thickness of the wall.

 

[rico_suave]

this is for my own loft.

I am based in Oldham, do you know any SE's in the area that I could contact.

 

[rico_suave]

the wall are aprx 110mm thick. the headers you see are next doors chimney

 

[tony1851]

the wall are aprx 110mm thick. the headers you see are next doors chimney

Ah, yes - can see that now. So if you do need steels, run from front to back.

On a more general note - you have taken up much of the bedroom space to get the stairs in. I can see that you need to get the stairs finishing more-or-less below the ridge because of headroom issues, but with a 42 degree pitch it will still be tight.
For single-room loft conversions, you can have steeper stairs up to 54 degrees; Google BS 5395 (Stairs for Limited Access in Dwellings).

Ultimately, is that house really suitable for a loft conversion without a dormer? You will need to lose at least some of the first-floor bedroom space to get the access in, and the loft room itself will be very restrictive as to where you put the bed and furniture. You could end up with 2 small bedrooms and how would that affect the value?

Have you considered dropping one of the bedroom ceilings to give more headroom? Those ceilings will be at least 2.7m and could come down easily by 300mm. Lower floor also = shorter stairs = saving more space.

 

[rico_suave]

I will be dropping the bedroom ceilings in the bedrooms to gain some extra height, will look into the stairs angle.

Don't think the steels will be a viable option as the locations will create a stepped scenario, and they will fall next to windows.

I will be changing the floor to just timber on the designs.

I know what you mean about the bedroom sizes think I may be squeezing too much into it.

The stairs layout is unfortunately the only one available due to the size of the bathroom. If I out the new route above the existing route I will have to make the bathroom even smaller.



I am now just unsure on the roof structure and how it can be supported with taking the upper purlins out. At some point the whole roof will have new batons and re-felted so I can carry out structural work then.

 

[freddiemercurystwin]

Personally I think that layout would be a 'fail' because you've taken up nearly half the first floor with circulation space.
Ideally, you put the loft stairs over the existing stairs to save space.

Agreed though then it seems he'll lose his family bathroom on 1st flr level, though his current proposal doesn't seem to work anyway due to the lack of headroom - see previous post.

 

[roganty]

Personally I think that layout would be a 'fail' because you've taken up nearly half the first floor with circulation space.
Ideally, you put the loft stairs over the existing stairs to save space.

Agreed though then it seems he'll lose his family bathroom on 1st flr level, though his current proposal doesn't seem to work anyway due to the lack of headroom - see previous post.

The first floor layout was unchanged from the OP's plan.
All I changed was the ground floor by switching the stairs around so they start from the front of the house instead of the back.
Saves the OP from building a corridor from the bottom of the stairs to an exit and losing downstairs space


Mine on the left, OP's on the right

 

[tony1851]

I am now just unsure on the roof structure and how it can be supported with taking the upper purlins out. At some point the whole roof will have new batons and re-felted so I can carry out structural work then.

If the rafters are continuous across both purlins (ie not done in separate pieces) then the continuity takes some of the deflection out.
Subject to checking by calcs, it might be possible to remove the upper purlin, at the same time stiffening the rafters with additional pieces (ie 5x2) screwed to the side of each rafter.

 

[^woody^]

the wall are aprx 110mm thick. the headers you see are next doors chimney

Are you sure that the party wall is not in fact 9" which stops at ceiling level and contiues in just 4 1/2" between the lofts only? That would be more common than a complete party wall only being in a single skin

If that is the case, beams can sit on the wall at ceiling height

 

[rico_suave]

ah I see, so potentially I could span some 5x2 from the bottom purlin to the top ridge to strengthen the roof, then remove the upper purlins......

 

[freddiemercurystwin]

Yes but you need an SE.

Can you please confirm once and for all the thickness of the party wall at first floor level. Not above first floor ceiling level. It would be very unusual for a party wall to be 100mm thick!

 

[rico_suave]

will check thickness tonight

 

[tony1851]

Yes but you need an SE.

Can you please confirm once and for all the thickness of the party wall at first floor level. Not above first floor ceiling level. It would be very unusual for a party wall to be 100mm thick!

Unusual - yes - but I have come across some up here over the years, mid-late 19th c. Clients say it's like living in the same house as the neighbours.