Wimpy No Fines Vents - How to block properly?

[Xander77]

Hi, I've googled this multiple times and I figure that after that many failures I could use a friendly ear. You guys turned up on a similar discussion so I figured I'd see what you think.

I'm living in what they term as a Wimpy no Fines house, which means it's walls are made by pouring two skins of concrete and filling the middle with what's best described as shingle.

Now as they had a naff boiler before all the rooms have at least one vent in them and they're big vents! We're talking like 8" diameter.

We have had the boiler replaced and the gas installer advised that we could block most of the vent up in the house. This wasn't much of an issue before but since we've had the windows and doors done it's a pain in the rear that there's still a draft! So I'm wondering what can be done to properly block these holes. I have been looking at black hole filters which look good but only come up to 5" diameter.

I've tried the vent covers but due to the position of the house and the vents these are inadequate to the point where in desperation I blocked the vent in the bedroom with expanding foam just to stop me waking up with a very stiff neck (it was either that or a bed scarf and I could really see myself being hung from that come the morning!).

So... any ideas?

I've read the suggestion of filling the hole with some kind of block and then plastering over it but I can see that leading to problems later so initially I'm trying to find some product which will fit to the vent or through it which blocks through draft and preferably a large amount of noise too.

Thanks for reading this far even if you haven't got an idea... I'm aware it's a lot to take in..

~X

 

[masona]

I'm trying to find some product which will fit to the vent or through it which blocks through draft and preferably a large amount of noise too.

How about cutting a couple of polystyrene insulation slab to 8" dia, push it inside pipe then re-fit the vent cover or maybe change the vent cover as well to open/closed type



http://www.wickes.co.uk/Polystyrene/invt/210802

 

[foxhole]

Don't forget to buy lots of bleach to deal with the mold you will create thru lack of ventilation.

 

[roughcaster]

Hi, I've googled this multiple times and I figure that after that many failures I could use a friendly ear. You guys turned up on a similar discussion so I figured I'd see what you think.

I'm living in what they term as a Wimpy no Fines house, which means it's walls are made by pouring two skins of concrete and filling the middle with what's best described as shingle.

I worked on Wimpey "no fines", (houses and flats) in the mid 60's, in Gosport and Portsmouth, (Hampshire), and i think you'll find there they do not have a cavity filled with shingle. It probably said it was 2 skins of plywood shuttering, filled with concrete, containing no sand, just cement and large aggregate.
The "No Fines" that i worked on, were a shuttered, single skinned, poured concrete structure, with a roughcast or similar on the outside, with Paramount Board lined walls on the inside.

 

[Xander77]

Thanks for the ideas guys.

Masona,

That sounds viable. One question, wouldn't the polystyrene degrade due to moisture and such? Other than that it sounds ideal. Just get some thick board, cut it to say a hexagon and fit.

Foxhole,

Yeah I did consider mold. I'm figuring if I only block some vents and try for some solution which allows minimal airflow, possibly indirect as the black hole products, and I'd be onto a winner.

roughcaster,

My apologies. I was told the correct term was 'Wimpy No Fines'. The walls are actually two layers of concrete with shingle in between though. Makes it a right pain to drill and no mistake. Hit a pebble and you've got to break it, hit in between and the drill shoots forwards like someone just snatched it out of your hands! We've also had one builder in tears who stripped his freshly recoated diamond wheel in one shot! It's hard stuff.

 

[roughcaster]

I know it's very hard to drill accurately into this type of structure.

 

[Xander77]

I know it's very hard to drill accurately into this type of structure.

Most of the time I'd just appreciate it if it'd stop laughing at my masonry drill bits + non professional drill like I was approaching it with a cheese stick!!

There has been one incident of perfect success. An SDS drill bit the size of my arm and a large Dewalt drill (24v I think). That cut like butter but other than that it's a pain!

 

[Monkeh]

Get yourself a decent SDS (low end Bosch is ideal and affordable) and some proper bits for it (I use Dewalt bits personally). Don't forget the lube (silicone grease on the shanks).

Go slowly and don't lean into it.

 

[foxhole]

Thanks for the ideas guys.

Masona,

That sounds viable. One question, wouldn't the polystyrene degrade due to moisture and such? Other than that it sounds ideal. Just get some thick board, cut it to say a hexagon and fit.

Foxhole,

Yeah I did consider mold. I'm figuring if I only block some vents and try for some solution which allows minimal airflow, possibly indirect as the black hole products, and I'd be onto a winner.

Minimum air flow will ensure maximum mold.

 

[ajrobb]

You could try expanded polystyrene as suggested and filling with a foam sealant (I don't know if these dissolve the polystyrene). Protect the outside with matching pebbledash and plaster the inside.

If the wall insulation is not up to much, consider positive input ventilation to control humidity.

 

[^woody^]

.... the gas installer advised that we could block most of the vent up in the house.

That's very bad advice

These no-fine walls are very cold and prone to condensation issues. Once you seal the house up then you risk getting condensation and associated mould in the usual places on the walls

Fit an external cowl or internal baffle if draughts are a problem, but sealing vents up is a bad idea

BTW, the walls are solid concrete with just the big concrete stones and cement and no sand (ie no fines) in the mix

 

[roughcaster]

BTW, the walls are solid concrete with just the big concrete stones and cement and no sand (ie no fines) in the mix

Exactly Woody!!!

 

[ivixor]

.... the gas installer advised that we could block most of the vent up in the house.

That's very bad advice

These no-fine walls are very cold and prone to condensation issues. Once you seal the house up then you risk getting condensation and associated mould in the usual places on the walls

Fit an external cowl or internal baffle if draughts are a problem, but sealing vents up is a bad idea

BTW, the walls are solid concrete with just the big concrete stones and cement and no sand (ie no fines) in the mix

I'm not so sure - Our house is the same wimpey no-fines construction. We have no vents at all - only one in the living room where the back boiler is.

No problems with condensation/damp/mould whatsoever. House is warm and dry!

 

[masona]

We have had the boiler replaced and the gas installer advised that we could block most of the vent up in the house.

As pointed out by woody - bad advice - I was under the impression you've got the okay to block some of the vents from the gas safe installer

This wasn't much of an issue before but since we've had the windows and doors done it's a pain in the rear that there's still a draft! So I'm wondering what can be done to properly block these holes. I have been looking at black hole filters which look good but only come up to 5" diameter.

Can you not use a bigger mesh cover and still use the 5" black hole ventilator? Having says that, you'll need to find out if reducing the vent size dia is acceptable

 

[^woody^]

I'm not so sure - Our house is the same wimpey no-fines construction. We have no vents at all - only one in the living room where the back boiler is.

No problems with condensation/damp/mould whatsoever. House is warm and dry!

May be so, but your house is not the same as the OP's (I assume) and you are not him.

If the property has vents then it had them for a reason.

The OP could just block them up with some rag and clingfilm and see how he gets on over the course of a year- 18 months, before deciding to block them permanently. But fresh air is better than no air