Small crevices in chipboard flooring joints (~1mm). Probably insufficient glue used. When rain fell, water leaked through (temporary problem before roof went on). 

However, sound passing between first and ground floors not ok.

How to seal the small gaps acoustically? Which particular acoustic sealant?

Just about any flexible material or filler will do, are you sure the noise is from the small gaps? More likely board movement acting like a sound board. Or transmission through the structure

2 minutes ago, markc said:

are you sure the noise is from the small gaps

New build in progress. No noise currently. Anticipating future noise, trying to seal.

Looking for particular brand / product to be recommended for these small gaps.

Okie dokie, good ole CT1 … every builders best friend

2 hours ago, markc said:

Okie dokie, good ole CT1 … every builders best friend

@WWilts buy in bulk as it will get used! 🙂 

Sealants are due a price rise of about 50%!

5 minutes ago, Mr Punter said:

Sealants are due a price rise of about 50%!

****! better get some more ordered then.

my builders merchant has said that they also stock OB1 which is cheaper. does it do the same job as CT1? anyone know the difference?

They are both said not to shrink, which matters in this scenario.

Assuming that one tube will suffice, this probably isn't the time to try the budget options.

4 minutes ago, saveasteading said:

the budget options.

On which: Sometimes the cheapest silicones will do the job, and you would wonder why the big names are so expensive. But sometimes it can be poor. I wouldn't even assume that one 'own brand' or budget purchase  was the same as the next as the retailers probably shop around to the cheapest manufacturer, then use the same name.

 

eg Stickslike say £8

Gripfill at say £3

No nonsense £2

 

The latter is possibly better for a skirting to plaster because it is thin and runny, and sits tight. (Gripfill a bit lumpy.)

But useless for timber to masonry...because it is thin and runny.

 

Silicone the same, as the cheaper stuff will sometimes fil a gap, but often need a second application. 

 

 

Everbuild Everflex ac50 seems suited to this situation. 100% to 200% elongation at break. 

On 01/04/2022 at 18:26, Thorfun said:

OB1 which is cheaper. does it do the same job as CT1

Virtually same ingredients. Minor differences.

On 01/04/2022 at 18:26, Thorfun said:

my builders merchant has said that they also stock OB1 which is cheaper. does it do the same job as CT1? anyone know the difference?

yes it’s crap - nothing like CT1 to use.