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Old 19th September 2019
Here for the gear

Two ceiling options - which is better?

Hi there,

I have a lot of trouble with upstairs neighbours – heavy footsteps, kids running, furniture moving, doors banging, etc. At the moment, our ceiling is 15mm drywall attached to wood joists, 50mm air cavity (with no insulation) and concrete slabs separating the two properties. They have a wooden/ laminate floor so impact sound passes easily through the rigid concrete below.

I’ll tear the existing ceiling down, put 50mm RW3 in the void and Sound clips to decouple from the joists (I’m using Oscar Iso Clip, minimizing space loss is important). I then have two options for the new ceiling (see below). One is more expensive and I’m wondering whether it’s worth it??

Option 1:
Two layers Soundbloc (15mm and 12.5mm) – totalling 22.6kg/m2
Green Glue between the layers (2xtubes per sheet), for good measure

Option 2:
15mm Phonestar Drywall (19kg/m2)
12.5mm Soundbloc (10.6kg/m2)
No green glue
Total of 29.6kg/m2
(phonestar is a sand-filled acoustic board – high mass, but also soft/ loose so they claim better soundproofing properties)

In both scenarios, perimeters/ joinings are sealed with isolation strips/ backer rod and AC95 sealant.

I've attached a drawing of my proposed setup.

My question is – which seems to be the better choice? Option 2 is more expensive and I can’t speak for all the purported benefits of phonestar boards, but they are higher mass - which might be more helpful than the Green Glue?

Any thoughts or advice welcome - Thanks guys!
Attached Files
File Type: pdf Schematic.pdf (327.6 KB, 13 views)