Boarding/Sheeting between the rafters and felt

[Kev1312]

Hi

 

I am currently cleaning out my loft space with a view to making it a more workable storage area and easily accessible. I had a redundant plastic water storage tank removed recently which had laid dormant for years prior to my purchase of the house which has now freed up a lot of space. 

 

Between the rafters and the felt there is wooden boarding which I presume would have been fitted at construction time. See photographs attached. The majority is still in place, albeit some is now kept in place with 2x4 battons attached to the rafters to keep in place. However there are 2-3 sections where the boarding has come away from behind the rafter and is now sagging down and can’t be push back in place or secured too easily.

 

I am looking for some thoughts or advice on firstly the primary purpose of this boarding and also what is the best way to try and resecure the fallen/sagging sections and put back in place.

 

I presume cutting out and trying to refix with the battons might work as opposed to try and force back in behind the rafters and risk it breaking in half. 

 

I presume this layer of boarding is common in loft spaces as an extra heat loss barrier and has a purpose still?

 

You will see from the photographs attached the offending section which is the biggest concern. 

 

Any thoughts or advice greatly appreciated 

 

 

 

Thanks

Kevin

 

 

[joe90]

I have never seen that before, looks like a fibre board. It’s a cold loft (insulation at ceiling level and ventilation to dry out any condensation). You could prop it up with battens on the roof timbers but I still don’t know why it’s there?

[BobAJob]

Looks like it's holding the roof felt in place like maybe some sections were replaced.  Kinda odd. 

[A_L]

16 minutes ago, Kev1312 said:

I am looking for some thoughts or advice on firstly the primary purpose of this boarding

 

Traditionally in Scotland six inch wide planks were nailed to rafters as 'sarking' this increased the strength of the roof in our weather conditions and slates (not tiles) would be directly fixed to them. My theory is that it is a  'sop' included to get building regs approval and has little strengthening effect (as evidenced by its fragility).

[TonyT]

My old Wimpey house in Edinburgh had this, probably the modern equivalent of sarking boards...

I never gave it much thought.

 

[Adam E]

Hi it was made by celotex among others usually  12mm thick it’s like fibre board with tar mixed through it 

Marley contract services used it on all the large sites in Scotland in the 1990 ‘s as a replacement for sarking boards 

if you google  (Wood Fibre Insulation Sarking Boards )

you can still get some results but it is a very poor replacement for traditional sarking boards or osb sheets

 

adam

 

[Temp]

17 hours ago, joe90 said:

 It’s a cold loft (insulation at ceiling level and ventilation to dry out any condensation).  

 

+1

 

A so called "cold loft" has the insulation at joist level. A "warm loft" has insulation at or above rafter level. 

 

A cold loft is meant to be well ventilated so that any water vapour (from the warm part of the house) that gets into the loft is removed by ventilation. There should be vents at the eaves that allow air to flow in one side, across the floor of the loft above the insulation and out the other side. That's the ideal set up anyway.

 

This means that the boards you refer to at rafter level are not for insulation. I'm inclined to agree with this..

17 hours ago, A_L said:

 My theory is that it is a  'sop' included to get building regs approval and has little strengthening effect (as evidenced by its fragility).

 

Your loft insulation doesn't look very thick. You might consider investigating grants for additional insulation although I suspect your existing insulation might need to be less than 2" possibly 4" and you might need to be on benefits.

 

If you do add more insulation you should preserve the air flow at the eaves. If you block that airflow you risk condensation forming in the loft. There are special "tunnels" you can buy that allow you to stuff insulation down into the eaves without blocking air flow. 

 

The roof is also a trussed roof which means pretty much every bit of wood has been designed to be only just strong enough. You probably already know you shouldn't go removing anything without advice and avoid storing massive amounts of heavy stuff up there. 

 

You can certainly use it for storage (of anything not damaged by cold) but regular access should be avoided. Try and keep the loft hatch closed as much as possible to keep water vapour out or it might just condense out on whatever you are storing.