How to fill old vent hole in external wall

FreshlyCutFlowers

I have installed a new tumble dryer that doesn't need the vent hole.
I want to fill the vent hole back up to avoid the chance of critters/anything coming through and it seems wise to avoid any small drafts.

My wall is external, brick, no cavity, with an external render.

Can anyone link me to the specific products I need to do this task myself?

I'm not very good at DIY and have never used concrete before but would like to learn.
There's a lot of different concrete types to choose from so I want to avoid selecting 'the wrong one'.

Thanks!

CliveOfIndia

One way of doing it would be to fill most of the hole with small smashed-up pieces of brick, then mix up some mortar to hold it all in place and cover it.

But to be honest, it's far simpler to just use a can of expanding foam filler.  Once it's cured you can sand it back and apply a thin coat of filler or mortar over the top to hide it.  You don't have to cover it with filler or mortar, that's purely for aesthetic reasons.

FreeBear

Expanding foam is called Bodger's Foam for a reason. Whilst it is very good and filling small gaps, it isn't going to work too well if you try to fill a 100mm hole in one go. It needs to be built up in thin(ish) layers or you'll find the middle doesn't foam up and harden.

Cutting lumps of brick a little smaller than the hole and filling the gaps with mortar is the correct way to do it. Breeze block (aerated cement block) would be easy to cut and shape to fill the hole. Being rendered/plastered inside & out, it doesn't matter too much what it looks like.

If you don't have any bricks/blocks to hand, ask your local builders merchant for a damaged/broken one, and they'll probably give it to you for free. B&Q or Wickes are likely to charge a nominal amount if you prefer to shop there.

FreshlyCutFlowers

CliveOfIndia said:

One way of doing it would be to fill most of the hole with small smashed-up pieces of brick, then mix up some mortar to hold it all in place and cover it.

But to be honest, it's far simpler to just use a can of expanding foam filler.  Once it's cured you can sand it back and apply a thin coat of filler or mortar over the top to hide it.  You don't have to cover it with filler or mortar, that's purely for aesthetic reasons.

I also have a handful of other items I may want to use concrete for soon, so was thinking it'd be a nice way to avoid buying too many things. I will likely make a different thread to get more steps on how to deal with them but here's a picture for the kind of jobs.

Can I use anything labeled 'mortar' or do I need a specific type? Can I use the same product for all of these, including the vent hole? I see screwfix has a 5 kg bucket of 'no nonsene mortar'. 

FreeBear

FreshlyCutFlowers said: Can I use anything labeled 'mortar' or do I need a specific type? Can I use the same product for all of these, including the vent hole? I see screwfix has a 5 kg bucket of 'no nonsene mortar'.

With an older property with solid brick walls, you should really be using a pure lime based mortar. I have a tub with a mix of lime putty and sand sitting in one corner. As long as the stuff remains damp (ideally with a thin layer of water on top) in a sealed tub, it doesn't go off. So when some mortar is needed, pour off the water, give it a good stir, and use. It can be used both outside and in for patching brickwork, cracks in plaster, and so on. Finishing coat for plaster is best done with a mix of chalk or marble flour and lime putty.

Not much you can do with cracks in concrete fence posts - Water will have got in and the steel reinforcement is likely to be rusting. Rusting steel can expand up to five times its original size and push the concrete apart from the inside. Repairing the cracks will be a purely cosmetic exercise, but even so, they should be OK for another 10-20 years.

FreshlyCutFlowers

Thanks - I won't bothers with the fence posts.
Will something like this do? https://www.limestuff.co.uk/non-hydraulic-lime-mortar/coarse-stuff-lime-mortar-oatmeal-8kg-tub-14812

I see it mostly comes in 25kg bags but I was hoping to avoid spending tons on this stuff as I'm unlikely to do my own repointing or something like that in the future.

FreeBear

FreshlyCutFlowers said:

Thanks - I won't bothers with the fence posts.
Will something like this do? https://www.limestuff.co.uk/non-hydraulic-lime-mortar/coarse-stuff-lime-mortar-oatmeal-8kg-tub-14812

I see it mostly comes in 25kg bags but I was hoping to avoid spending tons on this stuff as I'm unlikely to do my own repointing or something like that in the future.

Bagged will be hydraulic lime which sets in the presence of water. The 8Kg tub you link to contains non-hydraulic lime and sets by drying and carbonating in the presence of air - As long as it remains wet and in a sealed tub, it doesn't go "off" (unlike the bagged dry stuff). Just store it somewhere cool and free from frosts.

I have a couple of tubs containing non-hydraulic lime (otherwise known as lime putty), several years old now. Still good to use after "knocking up".

daveyjp

Fill a piece of vent hole liner with concrete, leave to harden and insert the plug into the hole.