Masonary Bodge Job – Advice Needed - hole too large!

[SirLancelot]

Fix that in with silicon or cement and it will look terrible. That would a typical "tradesman" bodge. Cut a square of treated wood and affix that with silicon and screws. The silicon should not be seen and will/should be used to seal the edge of the wood to prevent water ingress. Cut your hole in the wood and that's it. A bit more work but it will look neat. It will be weather proof and it wont look like a bodge job. Yes I do know tigercubrider suggested this as well.

Get a bit of stainless/ aluminium or wood/upvc and make a plate 50 mm bigger than the vent and fix it to the wall, with a 150mm hole in the centre

Must admit, my preference for heat transfer would be PVC because if you use stainless it will transmit the cold freezing external temperatures into the house faster, timber, if used should be pressure impregnated to avoid wood rot. Problem is using PVC the screw fixing into it can be a pain?

Other considerations?
1/. Mastic seal between the flange and the brick, watch out not to smear the mastic on to the exposed brick, a pain to get back off again.
2/. Pack the space between and all round the external of the vent duct within the wall thickness with Insulation that way you avoid a cold spot.

As for the gloves simple answer is that if the kit has to be returned no finger prints to incriminate the returnee ? just a thought ? after all you never know who is holding the finger prints paranoid or what? [were the vent kits made in any of the old Soviet Union states?

From Homebase / B&Q / Wickes - Could I get a UPVC (or PVC?) Panel that is about 180 by 180? If not - where?

It seems to me - the prioirty should be on getting a good seal to prevent water ingress over the long term? The panel has to be thick enough to transfer the load, to the mastic so it pushes up against the wall over many summer's / winters. Don't like the idea of using wood - as even when treated it will degrade and any resulting mess will only be visible after quite a bit of damage is done?

 

[John D v2.0]

It seems to me - the prioirty should be on getting a good seal to prevent water ingress over the long term?

You should have sloped the duct outwards to stop water tracking inwards. Other than that you have a cavity wall and the cavity is drained, so not much chance of water ingress even with a small gap.

 

[Tigercubrider]

Any upvc supplier will have supplies, although you will need to buy a bigger bit and cut it or ask the supplier to
https://www.ebay.co.uk/itm/9MM-SOLI...hash=item1c6e44f71d:m:m9ItxXr-13-_63zTLypbEyg

 

[noseall]

The other thing you could do (if the hole is large enough) is ex-foam in a 110mm 160mm platic drain pipe as a liner then glue the vent fitting into the liner. The liner can finish level with the skimmed plaster internally. This will end up a solid job.

This is how we do them from the outset because of the problems trying to mechanically fix (plug & screw) the vent terminal to the very edges of friable masonry.

Edit: Or go larger on the pipe if the fitting dictates. Looks to me like a 6" vent.....?

Edit II: Just read the OP. Use a short length of 160mm plastic drain pipe.

 

[SirLancelot]

UPDATE:

https://www.diynot.com/diy/threads/rate-this-job-cooker-hood-extractor-install.505036/

I would be really grateful for your thoughts on all the effort it has taken to get this far!

SL

 

[SirLancelot]

I'm very grateful to all those that have contributed thus far.

I need a little more help - just to complete the job - and am asking for some guidance:

My questions here are about learning something - including theory & best practice (for my education).

1. Clearly I need to 'make good' between the masonry, tube and grille.

A number of the 'all-in-one' cooker hood vent-kits that are be sold by selco, B&Q, wickes, screwfix etc - include the Aluminium tube (insulation free), the exterior grill, a few cable ties (and maybe a wall plate + screws). The instructions fully outline boring a the hole in the wall - fixing the grille and tube in-place - but literally - none of them discuss insulation of the the Alu-flex tube (or any additional back draft protection):

https://www.screwfix.com/search?search=cooker+hood+termination++kit

In our climate (I am asking members to expand on this) - during winter - I'd imagine there will be condensation on an Aluminium surface - and this could potentially cause some condensation pooling - especially at the bend of the tube - which could affect the cooker hood?

So - in terms of insulation of this type of Alu-flex pipe - what would be a sensible move here? Does it indeed need insulation - if so - what type?

[Still easily attended to - the pipe is not yet fixed into place - there is a downward slope outwards. Note - the black bag around the tube was simply used to protect pipe against masonry temporarily - please ignore].

2. What would be the best way to 'make good' between the tube & masonry - given it traverses through plaster>breeze block>insulation cavity>redbrick - from inside out.

3. The four flap gravity grill to be fitted - flaps around in wind. It's safe to say in winter - it will not protect against cold damp air - when windy. Do I need to add anything to mitigate against this - to protect the appliance & viability of the install over the long term?

4. Any other advice/comments/constructive criticism - is welcome.

I'm sincerely grateful - for any advice / contribution fellow members are willing to offer.

SL

 

[SirLancelot]

Must admit, my preference for heat transfer would be PVC because if you use stainless it will transmit the cold freezing external temperatures into the house faster, timber, if used should be pressure impregnated to avoid wood rot. Problem is using PVC the screw fixing into it can be a pain?

Other considerations?
1/. Mastic seal between the flange and the brick, watch out not to smear the mastic on to the exposed brick, a pain to get back off again.
2/. Pack the space between and all round the external of the vent duct within the wall thickness with Insulation that way you avoid a cold spot.

As for the gloves simple answer is that if the kit has to be returned no finger prints to incriminate the returnee ? just a thought ? after all you never know who is holding the finger prints paranoid or what? [were the vent kits made in any of the old Soviet Union states?

Now most of the apparatus positioned and measure right.

I need advice on whether I need to insulate the tube along its length & if yes - which type of the insulation I should use. Does it need to cover the entire length of the tube within the bored hole?