How best to raise boarded out area in loft to increase insulation levels

[marshian]

Bit of background - 33 years ago we bought the current house - it was built in 1982 and insulated to 1980 stds - Loft had 25mm of blown fibreglass loft insulation in the 75mm truss depth

 

When I looked up in the loft it was clear that it was getting blown around - so some of it I replaced with roll style loft insulation in 75 mm and other areas I boarded out to stop the existing insulation moving around. I had an abundant supply of free euro pallet sized 22mm chipboard so it was easy to do piecemeal and they went up thro the loft hatch easily.

 

I got power sockets and lighting up there as well as a decent loft ladder because I've moved the cold water store and CH header tank to make better use of the space (Well and to stop my back hitting the framework every damn time I went into the loft because it overhung the loft hatch)

 

That's how it stayed for many years - a few areas of the loft got extra insulation laid across the roof trusses another 100mm so at best in some areas I have 175mm in other areas it's just 75mm - so pretty poor by modern stds

 

I considered getting rid of the boarding but having the central area boarded out gives me good access to most of the loft without sicking my feet where they shouldn't and whilst it's only really got a few empty suitcases, Xmas decorations and a few sailing bits finding homes for them out of the loft would be difficult.

 

I'd really like to increase the depth of insulation in the boarded out area and replace the loft hatch with a modern one with better seals and now the weather is starting to turn this is my opportunity to plan and execute

 

I want to re-use the existing boarding where I can because it's already up there

 

I had considered 8 x 2 Joists but they works out at 9 kgs per metre and that sort of weight plus the boards already used is going to build up quite fast - then there is the cost of wood these days........

 

I looked at loft legs but meh......... sorry they just look flimsy and well I'm not convinced. I'm not a lard arse but I wouldn't trust them

 

Then I saw another thread on here where I-Joists were being used on a build - a couple of quick searches and it seems 220mm I-Joists are 3kg per metre

 

They'd be a heck of a lot easier to man handle up thro the house and the loft hatch and it would get me much closer to the 300mm insulation depth I'd like to get to.

 

All the internal walls of the house are thermalite blockwork and ground floor is replicated on the first floor so the roof trusses are very well supported but I don't want to put too much additional weight up there.

 

If I-Joists are prohibitive cost wise I could probably cut sheet OSB down and tile batten and my my own

 

Daft Idea or does it have some merit?

 

 

[marshian]

Oh and a picture might help - this one side of the loft from when I was moving the Cold water tank to a location that wasn’t overhanging the loft hatch

 

It’s the same length behind me and there are two legs of the roof going out left and right

 

House is a T shape so a lot of the roof structure is bloody hard to negotiate

[joe90]

If you only want to board the central section why not bolt 6 x 2  timbers to the verticals at the required height fir your insulation then board with your chipboard, not up to building regs but your not having a party up there 🤷‍♂️

[ETC]

[elite]

Loftzone do a product that looks more stable than the cheap legs:

 

https://www.loftzone.co.uk/shop-storefloor/storefloor/?attribute_kit-size=Starter+Kit+1.2m+x+2.4m

 

Another member did an install here: 

 

Edited September 10 by elite
broken link

[marshian]

37 minutes ago, joe90 said:

If you only want to board the central section why not bolt 6 x 2  timbers to the verticals at the required height fir your insulation then board with your chipboard, not up to building regs but your not having a party up there 🤷‍♂️

 

Considered it but felt it was probably not the best place to put any load

[marshian]

30 minutes ago, elite said:

Loftzone do a product that looks more stable than the cheap legs:

 

https://www.loftzone.co.uk/shop-storefloor/storefloor/?attribute_kit-size=Starter+Kit+1.2m+x+2.4m

 

Another member did an install here: 

 

 

Was an option - last year when I was thinking about it - got as far as costing it out and got to £500 without any insulation cost - it's good but it's expensive and I'm not sure it's going to be any lighter

[G and J]

I’ve been thinking about our loft, insulation and access.  We will be storing v little or maybe even nothing up there, but there’s Solar and probably a hot water header tank which may require the occasional bit of maintenance.  
 

It occurred to me that I could use soft insulation between the chords of the fink trusses, then put a walkway down the middle made out of a sandwich of:

1. the cheapest material I can find (or salvage from the demolition);

2. some seconds quality PIR or EPS;

3. topped with again, cheap or reclaimed boarding.

 

Then that’ll give me a sensible walkway, good insulation under that walkway, and I can put loads of soft insulation to the sides of the walkway and never need to compress it or fart around finding trusses to stand on whilst worrying about popping plasterboard ceilings.  
 

Could there be any mileage in something like that for you?   Would one even need a walkway in the bottom or, given the rare use, just put the PIR straight on the trusses (which sounds sooooo scary!)

[bassanclan]

Loft legs

[marshian]

10 minutes ago, G and J said:

I’ve been thinking about our loft, insulation and access.  We will be storing v little or maybe even nothing up there, but there’s Solar and probably a hot water header tank which may require the occasional bit of maintenance.  
 

It occurred to me that I could use soft insulation between the chords of the fink trusses, then put a walkway down the middle made out of a sandwich of:

1. the cheapest material I can find (or salvage from the demolition);

2. some seconds quality PIR or EPS;

3. topped with again, cheap or reclaimed boarding.

 

Then that’ll give me a sensible walkway, good insulation under that walkway, and I can put loads of soft insulation to the sides of the walkway and never need to compress it or fart around finding trusses to stand on whilst worrying about popping plasterboard ceilings.  
 

Could there be any mileage in something like that for you?   Would one even need a walkway in the bottom or, given the rare use, just put the PIR straight on the trusses (which sounds sooooo scary!)

 

Having insulated the suspended ground floor with PIR from the crawl space below I really don't want to have to deal with PIR again

 

Cutting it down so it fits thro the loft hatch fills me with dread...........

 

I considered removing some roof tiles and battens so I could post it thro in full sheet size to avoid cutting it and then making good but removed it from my thought process........

 

I do like the walk way idea for access but I need a storage area even if it's capacity is limited

[joe90]

56 minutes ago, marshian said:

 

Considered it but felt it was probably not the best place to put any load

The loading will be on the  triangulation joins which are the stiffest part of the loft construction. Look at @ETC Post above for loft storage idea,s 

Edited September 10 by joe90

[marshian]

13 minutes ago, bassanclan said:

Loft legs

 

Thank you but I've discounted that as an option - you really do need T&G boards to make that even half decent and I would like to reuse the existing board that aren't

Edited September 10 by marshian

[marshian]

1 minute ago, joe90 said:

The loading will be on the  triangulation joins which are the stiffest part of the loft construction.

 

I'm sure you are right but my brain can't grasp that. What my brain can deal with is that the skimpy roof trusses are well supported by the wall structure underneath so any load is spread across a wide area

[joe90]

1 minute ago, marshian said:

 

I'm sure you are right but my brain can't grasp that. What my brain can deal with is that the skimpy roof trusses are well supported by the wall structure underneath so any load is spread across a wide area

Yes the “skimpy” trusses are triangulated to make them stiff hence they can carry the roof load without large timbers like the ones used in older houses. Draw me a diagram of your trusses AND the walls underneath and I will show you what you’re unable to understand. 👍

[G and J]

10 hours ago, joe90 said:

Draw me a diagram….  … and I will show you what you’re unable to understand

If you did that for me I’d have to draw Everything, Everywhere, and all at once!  :-0

[G and J]

10 hours ago, marshian said:

Having insulated the suspended ground floor with PIR from the crawl space below I really don't want to have to deal with PIR again

Is PIR that bad to work with?

[marshian]

24 minutes ago, G and J said:

Is PIR that bad to work with?

 

It's not the nicest material to work with - I think If I invested in a hot knife/wire cutting system it might have been better but using a sharp fine saw to cut 56m2 of 75mm PIR sheeting into individual joist filling slabs wasn't much fun

[marshian]

28 minutes ago, G and J said:

If you did that for me I’d have to draw Everything, Everywhere, and all at once!  :-0

 

I'm trying to keep it simple because I am!!!

[G and J]

1 hour ago, marshian said:

 

I'm trying to keep it simple because I am!!!

I know that feeling.

 

So a hot wire won’t set the PIR alight then?

[Nick Thomas]

The LoftZONE legs are fine, but expensive - and still not particularly stable. I installed them so the solar people wouldn't be messing around standing on the rafters, but they were quite critical of how it moved underfoot

 

The installer was a big guy carrying a big battery through ^^

Edited September 11 by Nick Thomas

[Mr Punter]

2 hours ago, marshian said:

- I think If I invested in a hot knife/wire cutting system it might have been better but using a sharp fine saw to cut 56m2 of 75mm PIR sheeting into individual joist filling slabs wasn't much fun

 

1 hour ago, G and J said:

So a hot wire won’t set the PIR alight then?

 

Hot wire is only good for polystyrene, not pir / pur.

[marshian]

1 hour ago, G and J said:

I know that feeling.

 

So a hot wire won’t set the PIR alight then?

 

I guess depends on the speed you run it thro the PIR - I didn't investigate it any further than ouch £400 that's not gonna be a cheap bit of kit for a single usage

 

If I was doing a complete house suspended floor and warm roof I might have considered it

[joe90]

Yes loft roll is a lot easier to work with squishing into place , with poly best to cut undersized and foam around it to make tight and glue it in place.

Edited September 11 by joe90

[marshian]

On 10/09/2024 at 23:00, joe90 said:

Yes the “skimpy” trusses are triangulated to make them stiff hence they can carry the roof load without large timbers like the ones used in older houses. Draw me a diagram of your trusses AND the walls underneath and I will show you what you’re unable to understand. 👍

OK roof trusses

 

 

Boarded Loft area I want to raise up is the centre section

6.9 m length by 2.1 m width with 13 trusses roughly 60 cm spacing (two at each end are closer)

 

Walls underneath I’m working on because the house is a weird T shape and every time I draw it out it looks wrong and the walls don’t fit right

[marshian]

Okay better than my scribbles

 

floor plan (upstairs)

 

Main loft area runs right to left and has the dividing wall between bedrooms at one end and and stairwell under the other end

 

Floor plan (downstairs)

 

 

All walls upstairs are basically repeated down stairs (and go right down to the concrete slab under the suspended ground floor where I spent a long time insulating between the joists in the crawl space)