Installing Posi Joists - Best Method

[richo106]

Good Morning 

 

The builders have finally started on our project and all being well will be up to first floor height in couple weeks (weather dependant)

 

To help with times and cost I will be installing the joists along with my joiner mate

 

The joists will be 225mm deep and the plan/layout (see attached) I have from the joist company is too drop the joists on the inner block work. Is this the best method to do this? We are focussing on air tightness also so was going to ask builders to point around the joists (I am happy to sort after aswell) but is there to consider when installing them?

 

Daft question: - Do the builders leave a gap to drop them in or do I drop them all in first so they can brick around them? Are they heavy enough to stay square or do they need some kind of fixing?

 

Would people wait until all steel beams in place or take measurements from the blues/drawings? The drawing is slightly wrong as the beam for bi fold is lower so joists will run on top of that?

 

My only concern if we wait until everything in place then it will hold everything up 4 weeks while waiting for delivery

 

Any advice/information greatly appreciated

 

Cheers

[ProDave]

Make sure the brickies do NOT build up the end walls (the walls the joists are not resting on)  You will need the ends clear to slide the strong backs into the joists.  Only when those are in can the brickies build up higher.

[Thorfun]

consider a Tony tray for your air tightness around the joists.

 

https://forum.buildhub.org.uk/search/?&q=Tony tray&quick=1&search_and_or=and&sortby=relevancy

 

 

[joe90]

Or use brickwork hangers!

[Miek]

Pocketing the joists Into the wall is bad for airtightness. A Tony tray works. Or resin fix a ledger to the walls (after parging) and hang joists on hangers

 

[richo106]

2 hours ago, Miek said:

Pocketing the joists Into the wall is bad for airtightness. A Tony tray works. Or resin fix a ledger to the walls (after parging) and hang joists on hangers

 

I did think of this method, obviously this would require more work and would have to ensure the fixings are really good.

 

I was thinking if the joists are pointed up well by the builders and was thinking I could use air tight paint around the joist before I parge coat 

 

this would also make the strong back tricky

Edited November 20, 2022 by richo106

[Miek]

I didnt find it much work to fit the ledgers, just nail on the hangers before lifting  them. Fixings are just 12mm studs 2 every 800mm ( I just guessed this spacing) . I love resin anchors,  but they are slower In the winter.

 

If your webs are open and you need strongbacks I can see the difficulty.  Mine were osb closed web so no strongbacks. 

[richo106]

We are finally getting to the point when we will be installing the first floor joists. Originally I was just going to rely on good pointing/good workman ship to overcome the airtightness issues with joists sitting on the inner lead blocks.

 

however re-visiting this aspect I am leaning towards the Tony tray method. 
 

Could anyone recommend some material/size of material to use?

 

I am using the picture attached (from BH) as a guide, I know this is a daft question but could anyone also recommend tacks please

 

Many Thanks 

[richo106]

https://www.insulationsuperstore.co.uk/product/manthorpe-joist-seal-225mm.html?utm_source=awin&utm_medium=affiliate&utm_campaign=369493&awc=25117_1671494161_92b65a5e3c349fb0f8cae83b3a61e5eb
 

another option I have found is these manthorpe joist seals, has anyone used these? They seem simple to fit and effective!?

[Canski]

9 hours ago, richo106 said:

We are finally getting to the point when we will be installing the first floor joists. Originally I was just going to rely on good pointing/good workman ship to overcome the airtightness issues with joists sitting on the inner lead blocks.

 

however re-visiting this aspect I am leaning towards the Tony tray method. 
 

Could anyone recommend some material/size of material to use?

 

I am using the picture attached (from BH) as a guide, I know this is a daft question but could anyone also recommend tacks please

 

Many Thanks 

I like this idea. I must admit that in 40 years of bricklaying I’ve never been asked to do it. Every day is a school day. It’s a bit of work with the mesh but I was wondering if it was modified to a 50 mm down stand sealed against the blockwork with CT1 for example would it be as effective. Also on the top we normally fill level with the top of the joists before restarting. This could then be sealed to the masonry and lapped over on to the joists and fitted below the flooring. Just a thought. as far as the manthorpe units go they seem a bit pricey and I would need a few different sizes to cover the end of various width joists. 

[BadgerBadger]

Just coming up to our joist installation - what is the benefit of doing the above vs. using masonry hangers?  It appears to be much more fiddly.

[Canski]

30 minutes ago, BadgerBadger said:

Just coming up to our joist installation - what is the benefit of doing the above vs. using masonry hangers?  It appears to be much more fiddly.

Nothing really. Joist hangers are fine but personally I’d rather have my joists on a  wall than a hanger. 

[Dave Jones]

hangers better for thermal bridgeing/air tightness.

[richo106]

Hi

 

After speaking to my builders and looking through BH, i have decided to go with the Manthorpe Joist Seals, this is the slightly more expensive option but I feel most comfortable with this solution

 

I have 45 x 75mm x 225mm Joists and 2 x 150mm (doubled-up 75mm) joists which I can get the Manthorpe joist seals for

 

However there is 2 x 125mm joists that Manthorpe don't have a seal for....what are the best options for these two? Just ask the builders to pay particular attention pointing up?

 

I was planning on using air tight paint around the joists and floor junctions and then parge all over?

 

Many Thanks