Can you remove Struts in the Loft?

[Fiddy]

Hi,

I want to maximise the space in the loft area of my 1960s 3 bed semi. I plan to remove the ONLY two diagonal Struts which make a massive V in the roof space. There are 4 other Struts but these are vertical.

As pictures are better to explain I took a couple and marked them up with sizes et. All measurements are in mm.

Question: Is it is possible to remove the two Struts (F) completely?

Question: Could I then support the Purlin (A) with many additional vertical struts (B) attached to (C) instead? note: already have 4 of these marked (B). (i drew them in red below).

Note: The Struts (F) are supported by a load bearing wall.

Note: (C) sits on a loadbearing wall at several points on both sides of the ceiling also but it isn't very thick at (45x100).

The span of the boarded out floor is (2700mm or 8.75ft) width by (5800mm or 19ft).

The strength of the floor isn't really my concern as I've had well over 300 lbs of weight up there. My real concern is the Perlin (A) not being strong or large enough to fully support the roof tiles above (E).

Any advice would be great...

Take care,

Fiddy

 

[Deluks]

'C' the binders are usually there to help hold up the ceiling joists and keep them straight and parallel. You cannot place any additional loading on these binders.

The purlins 'A' are holding up the rafters (the main bit of the roof that the tiles sit on) the weight that these purlins are taking is transferred into the load bearing wall 'E' via the diagonal struts 'F'

What you are proposing takes the loading of the roof into the loadbearing wall, and transferring it into the binders which have no continuous support beneath them.

I think you are smart enough to now figure out the answer to your own question.

This is why steel is often used in loft conversions, they basically replace the binders, but have enough strength to take all the loading without buckling, and transfer the roof load into the load bearing walls, in pretty much the same place as the current binders do.

To do what you want to do will need a properly specced engineers solution, and will cost about a grand at the very least.

 

[Fiddy]

Thanks for taking to the time to explain things, great reply thanks.

So.. just to make sure... I would run steel from the gable end the full length of the loft ON BOTH SIDES to the other side and cement it in place... on top (but not resting) of were the BINDERS (C) are currently.

Then use the new steel as a support to run or "prop" the Purlin (A).

The steel that you mention, any chance anyone can expand on what sizes or any "builder talk details" I would need to support the load of the roof?

Can you purchase H steel in peices and bolt them together?

Completely new territory for me. I'll do some more research on the net etc but any advice would be great.

p.s if you think you can do the job for a grand, please message me

Many thanks again..

Fiddy

 

[sanj.varah]

you need to calculate your loading that your steel beam will take. This is based on a number of equations but we'll get down to the business one.

stress = Bending Moment / Section Modulus

Each I beam - not H beam. or RSJ as they are often called, has a specific section modulus. Generally speaking if you make the beam twice as thick it becomes 8 times stronger. You have to size the beam so it doesn't exceed the yield stress of carbon steel which is around 130MPa.

If you can't be bothered to do the calcs, and frankly in your position I wouldn't. I would simply replace whatever wooden beam you take out with the same outer dimensions in steel. This will probably give you a safety factor of at least 3. But do this with caution as you will be moving the loading from midspan of the rafters further away, so you would be better off beefing the rafters up as well. If you make them piggy back, you've probably made them 6 times stronger (allowing for losses) add the steel and you are probably left with a roof that was stronger than before.

Disclaimer: I can't be held responsible if your roof falls down!

 

[Deluks]

What is being discussed here is the main structural job when doing a loft conversion. To alter part of the roof will probably require notification to building control.
I'd suggest getting a structural engineer to advise and do the calcs. Even if you aren't doing a full loft conversion, getting the steels in for a potential 'proper job' is a good idea, and better than doing a bodge job/semi conversion which might need to be removed if you sell the house. For lots of reading, simply research all the threads in this section, search for all 'loft conversion' posts. Also get a good book on loft conversions from the library so you have an idea of what should be done and why.

My £1000 estimate included cost of materials, fees and basic engineer calcs w/out a site visit but not labour. Thats the tricky part

Can be easier to get steel up there in sections that then bolt together. These will have to be designed and fabricated though, and you will need a couple of strong mates to help. (I can help out for £1000 )

At 19ft I reckon you'll be needing steel no less than 8x4, heavy stuff and unless using bolted sections or back to back channel, will need to be craned in (more money!)

Don't just take my word for it though and go for it. Without the all important calcs your work will be in vain. If you undersize and the council find out then you'll have to rip it all out and do it again properly, and they'll probably fine you too. Probably worth a mention.

 

[sanj.varah]

Can the council actually bust you for taking out a purlin? I didn't think they could do that unless you made the house unsafe.

 

[Fiddy]

I've had 2 independant SEs looking into it. Things looked good as both had indicated that I have load bearing walls that i should move the struts to and looked into a new floor. Simply means using alternate spots for the new floor and support points maybe lose a little floor space elsewhere then remove the old struts...

They both want to charge me a fortune for common sense with plans and paperwork etc... who can blame them as they need a living but anyway forget that part... I've been reading up, bought a few very good tradesmen a few pints down the local... carried out my "own" installation hanging a floor with wood, not steel. It is due to be inspected in 3 weeks. Quoted 6 grand, so far its cost me just over 1.5 in mats.. lets see if it passes the BI.

I'll keep u posted.. thanks again for your advice all

Fiddy

 

[Deluks]

Got some more pics for us then?

 

[Snooie]

I have loft space...obviously and want to board it out to use as storage. BUT where the apex are there are wood lengths like hurdles running across on say every other apex, can i remove these and put upright struts in their place? im tryin to upload a foto but dont no how to do this.
i think i have lol. in black are wot i call the hurdles and in red is where i want to put wot i call srtuts to replace the hurdles
Chris
http://i1229.photobucket.com/albums/ee479/Snooie71/HURDLES.jpg

 

[Snooie]

I have loft space...obviously and want to board it out to use as storage. BUT where the apex are there are wood lengths like hurdles running across on say every other apex, can i remove these and put upright struts in their place? im tryin to upload a foto but dont no how to do this.
i think i have lol. in black are wot i call the hurdles and in red is where i want to put wot i call srtuts to replace the hurdles
Chris
http://i1229.photobucket.com/albums/ee479/Snooie71/HURDLES.jpg[/QUOTE]

http://s1229.photobucket.com/albums/ee479/Snooie71/?action=view&current=HURDLES.jpg

 

[Snooie]

I have loft space...obviously and want to board it out to use as storage. BUT where the apex are there are wood lengths like hurdles running across on say every other apex, can i remove these and put upright struts in their place? im tryin to upload a foto but dont no how to do this.
i think i have lol. in black are wot i call the hurdles and in red is where i want to put wot i call srtuts to replace the hurdles
Chris
http://i1229.photobucket.com/albums/ee479/Snooie71/HURDLES.jpg[/QUOTE]

 

[Squellie]

Hi I'm looking to move item b in you picture can it be done

 

[catlad]

Fiddy was all guns blazing but he never came back after building control came and inspected!!!!!!!!!!!!