# Drylining Hollow Block Wall



## Rosencrantz (31 Jan 2016)

We recently bought a 1960s semi d which is constructed of hollow block wall with no insulation. 

We intend to extend around the side and back in a number of years - external insulation is not an option at this time. Therefore we are looking for a spec for drylining.

As I see it there are 2 options

Option 1 - Insulated board - 72.5mm foil backed insulated board (60 insulation /12.5 plasterboard/3mm skim)

Option 2 - "traditional" - batten out/friction fitted insulation between battens/intelligent vapour control lawyer/'service zone within counter battens with extra insulation. (This is derived from "breaking the mould" series as published in Construct Ireland)

Both meet SEAI criteria.

Clearly option 2 is better. My concern is that it requires greater skill and may be more likely to be compromised in construction. Also its more expensive.

Therefore, I'm inclined towards Option 1 - foil backed insulated board. Does anybody have thoughts on this for this hollow block application? Is there an alternative?

Thanks


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## JohnJay (31 Jan 2016)

I went with option1 about 5 years ago on a 1920's mass concrete house. Worked perfectly, no dampness or mould, but the walls were in good shape before they were slabbed, no rising damp, etc. 

My only bugbear is that its impossible to attach anything heavy to the walls after its done (shelves, curtain rails, etc). I don't have any kitchen cabinets or wardrobes on external walls, but the 60mm of insulation would make it tricky to mount them if I did.


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## Sammy's Daddy (2 Feb 2016)

If you go like JohnJay ...... and you know the heights that you'll be fixing things to ....... rout out a 3" x 2" groove to fit same size timber. With the insulation board on the ground (routed side up), try the 3 x 2 for size and if OK spray some foam into it. Then fit the 3 X 2 in the void, put some polythene over the timber and place a concrete block on top - until the foam cures. This allows the 3 x 2 to be flush with the insulation and will take lots of weight.


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## shweeney (2 Feb 2016)

JohnJay said:


> My only bugbear is that its impossible to attach anything heavy to the walls after its done (shelves, curtain rails, etc). I don't have any kitchen cabinets or wardrobes on external walls, but the 60mm of insulation would make it tricky to mount them if I did.



could you use these things: http://www.woodiesdiy.com/Product/black-and-decker-5mm-hammerin-wall-fixing-pack-of-25/20902/1.5.2.9


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## Branz (2 Feb 2016)

Rosencrantz said:


> 1: Both meet SEAI criteria.
> 
> 2: Is there an alternative?


1:What exact criteria have you in mind here? 
What do the criteria say about where the dew point will be in the internally insulated wall.
Whats the plan for internal walls butting onto external walls?

2: what is the internal finish on the external walls? Gypsum based skim?

whats the cost differential between EWI and Option 2?

Does your expected budget stretch to EWI?

What are the floors: suspended timber down stairs.


I would wait for the EWI option and in the meantime address the heat loss though the house not being air tight enough.

The expectation for energy prices is to stay low for a few years so I wouldn't panic re the dry lining. 
Its not the proper long term answer.


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## Leo (2 Feb 2016)

shweeney said:


> could you use these things: http://www.woodiesdiy.com/Product/black-and-decker-5mm-hammerin-wall-fixing-pack-of-25/20902/1.5.2.9



[broken link removed] will do a better job.


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