Loft Conversion Cinema Room - Floor Insulation

Dazza the Stag

Novice Member
Im really excited to be at the early stages of converting my loft which already has attic trusses and will give me a space of around 4.5m x 13m, half of which I would like to use as a cinema.
I want to get it right from the beginning and am taking up the thermal insulation and replacing it with acoustic. This will sit above the 1st floor plasterboard ceiling and in-between the floor joists of the loft conversion.
The floor joists are at 400mm middles so I want a product that will fit without spending too much time cutting
There are many products and 2 that I have narrowed down to are
Rockwool Sound insulation Slab and
Knauf Earthwood Acoustic Roll
From what I have read at 100mm thickness both will meet the Building Regs requirements Part E, however the Rockwool is around 3 times the price. Is there a significant different between the 2 products apart from the price, I would really value some opinions, as I don't want to waste my money on something that adds no value but if its significantly better then I will consider it.
Thankyou

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adam-burnley

Distinguished Member
Yes quite a bit of difference. Rock wool is denser and so more solid.

Rock wool is actually really easy to cut with a regular kitchen knife. It wouldn't take long at all for your size room.
 

Dazza the Stag

Novice Member
Yes quite a bit of difference. Rock wool is denser and so more solid.

Rock wool is actually really easy to cut with a regular kitchen knife. It wouldn't take long at all for your size room.
Many thanks Adam
Just read through your build and it looks great, raised many more issues than I had even considered lol
I’m not sure if you found the same thing but it always seems as though there are arguments at the opposite ends of the scale, i have read several threads that suggest to just put in the cheapest acoustic insulation you can as long as it meets buildings regs for the floor, it is one of those things that I only want to to once though so I might invest in the more expensive denser option.
 

Reyreyrey

Active Member
I have a similar loft space and would love to convert it into a cinema room one day.

Will be bookmarking this thread and following along. No pressure op :D

Good luck!
 

Dazza the Stag

Novice Member
That's a cracking space you have there, looking forward to reading how your room progresses :smashin:
thanks - I even have the 47 sheets of plasterboard up there ready from 17 years ago ! Unfortunately the 18mm flooring is now not up to building regs and I will have to replace with 22mm 😒
 

shodan

Distinguished Member
What an amazing space! Sadly my loft is tiny with a very low roof. 😢
 

Dazza the Stag

Novice Member
First step of a very long process today, cleared all of the necessary stuff out of the loft - wife wasn't too stuffed that one of the bedrooms is stacked floor to ceiling now lol
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Dazza the Stag

Novice Member
I do have a couple of questions if we have any electricians here. I want to ensure that any electrics in the space where I am going to lay flooring is neat and tidy and can be readily accessed either from the eaves of the loft space or from below. There isn't much fortunately, but the bits that do concern me are some downlighters and associated wiring. I will be laying 100mm of acoustic slab and ideally i guess this should go over those lights. My question is therefore,

1) although the acoustic slab says that it is in no way flammable,should i purchase some form of fireproof hood to place over the back of the lights and if so are there any suggestions and

2) the wiring isn't the most professional I have seen and comes together in a terminal block, in one place there are several lights merging into the one block. I would like to extend this point to the eaves if I can, is there a much way way of doing this, lite a mini junction box, so the wiring can be neatly laid out and protected as opposed to being wrapped in electrical tape ?

Any help or suggestions much appreciated.

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Dazza the Stag

Novice Member
I have decided to go down the more expensive Rockwool acoustic slab - hopefully the added density will make a difference - be warned though that its worth shopping around as I obtained a much better price than I could find advertised by contacting a couple of builders merchants. Haven't bought it yet though so if you know of alternatives sellers then please shout
 

inzaman

Moderator
I am no electrician but in my garage to add additional lighting i used Wago connectors eight way (you can get others) and the correct Wago box. really easy to use and looks professional and is secure once connected up properly. In my opinion they would be ideal for this.
 

AmericanAudio

Active Member
AVForums Sponsor
From our intepretation of building regs, if you are technically adding another floor (room) above the 1st floor then you should have fire-hoods over all the downlighters in the 1st floor ceiling.

At that sizes they are not going to be expensive, so as you say, worth doing right first time and at least you have easy access at the moment.
 

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