sound proofing a loft

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Member Since: Apr 04, 2008


Im planning on moving my studio/practice space up to my loft in order to give me more room, a better environment to mix in (especially dealing with bass response as my current room is crap and very inaccurate) and also, hopefully, insulate enough as to keep the neighbours happy! So I just wanted to see if anyone can see anything wrong with what im planning.

FIrstly, loft floor space is probably about 7m by 4m, but the roof is on both sides along the 7m length sloping to the top above your head. Although I have insulation underfoot under the floor boards, I dont have any in the sloping rafters which is where most of my sound/heat will escape. So, I found some rockwool on special offer for around 2 a roll, so to cover the hole sloping roof area, would cost under 60 - which i thought was pretty amazing.

So I was going to install the rockwool in the rafters (Ive also heard its water resistant? which can only be a good thing as the roof has some damp patches from loose slates which i plan on fixing anyway) and then, ive heard that you should have some kind of water barrier to prevent condensation? So I would just staple some plastic sheeting on in front of the rock wool to maybe keep it in place in the rafters and stop it from falling out, followed by some kind of plywood or plaster board on the front in order to get a smooth and tidy finish along with some extra sound insulation points.

At the ends of the loft - one side is attached to a neighbour, the other is free - I was going to build a wall on each side, to hide the water heater as well as provide some extra sound proofing, especially to my neighbour. These walls would be built with plasterboard or plywood on each side with more rock wool in the middle.

Then once the space is concealed, I was going to use whatever rock wool I have left to maybe build some bass traps for the corners as per here - (

So! my question is really.. am I on the right lines? Im taking this approach as im on a rather tight budget, but obviously want to do things as right as I can so its not a wasted effort.

Many thanks for any advice!


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MASSIVE Mastering, LLC
Since: Aug 05, 2008

Feb 26, 2010 12:13 pm

I'd call it the right direction... And don't underestimate what *two layers* of 5/8" (even 1/2" for that matter) drywall can accomplish... That's a big deal (and a good deal). Insulated studs with 2 layers of drywall is about as effective (and cost-effective) as you can get on a tight budget.

Since: Apr 03, 2002

Feb 26, 2010 01:08 pm

I'll second respect for drywall, it's a great surface, is reasonably priced and readily available...gotta love it.
Since: Apr 04, 2008

Feb 26, 2010 04:04 pm


Thanks guys!

Sound as good as you play
Since: Dec 23, 2008

Feb 27, 2010 03:26 pm

One thing I would recommend is consulting with a professional builder or roofer before you put anything in the rafters. If you know what you're doing, then ignore this post.

Based on the gigs listed on your website, it appears you are in Scotland, where the climate isn't all that different than here in the northeast U.S.

You've got the layering of materials correct. People often put the plastic on the outside of the insulation, thinking that its job is to keep out the moisture. In fact, the warmer inside air holds more moisture than the colder outside air. The plastic keeps the moisture inside the house and out of the insulation, rafters, etc.

The other mistake people make is obstructing airflow under the roof deck. Your slate roof is designed to "breathe" in a certain way. As long as there's space between the rockwool and the exterior roof deck, I would guess you're ok. On the other hand, I'm a banker so don't rely on my opinion.

Good luck.
Since: Apr 04, 2008

Mar 01, 2010 05:22 am

hey doug,

thanks for your post, yeah thats the general idea i had - having two layers of plastic both near outside and on the inside.. ive also decided that ill use some vertical and horizontal beams in the loft that basically create a boxed room as opposed to a triangular room (kind of a square within a triangle type thing), so it turns out the insulation that will be on the diagonal rafters, will only be there for about a meter so i dont have much length to worry about in keeping an air space between the plastic and the outside tiles.

thanks very much for your help!


Sound as good as you play
Since: Dec 23, 2008

Mar 01, 2010 01:38 pm

In the states you can buy airflow channels made of styrofoam or rigid plastic that are placed against the outer roof and ensure proper airflow. You might look for something similar if there's any chance airflow could be blocked in those one meter sections.

Here's an example:

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