Masonary Bodge Job – Advice Needed - hole too large!

[SirLancelot]

New cooker hood - req 150mm to cover warranty - powerful unit.

Purchase “150mm Rigid Aluminium - Manrose Cooker Hood Kit”.

In box instructions – bore a 720mm correction 172mm hole for ease of fitting. So I did (Pics).

Next - looked at the rest of the kit. Included gravity grille = 150mm. Included aluminium duct (internal) = 620mm! Up against the end of the tube – 20mm gap from plastic coupling (gravity grille) – to inside of. Very poor pairing in my opinion. To get a seal against the coupling of the Grille, the aluminium duct - has to be severely folded.

Returned Manrose kit! Hole already made - to big!

Ikea - aluminium ducting (accurately 150mm internal dia) + Separate 150mm Grille (in pics) – perfect coupling – great fit.

Help: How to reduce the size of the hole – specifically so I can get a proper seal when affixing that grille to the wall, using screws. What is the right way to be resolving the gaps?

What do I need to buy/do to get this done properly? The seal needs to be good and must last.

(Cavity wall with insulation).

P.s: Any of these correct? : http://www.u-can.tv/products-category/outdoors/

 

[Tigercubrider]

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

 

[^woody^]

What's wrong with your hands?

 

[KenGMac]

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?

 

[pilsbury]

Seeing as the grill almost covers the hole, couldn’t you install the vent pipe work then mortar well around it, let it cure then fix the vent in place? You wouldn’t see much of the mortar at all.... then you’ve got it cracked.

 

[TicTac]

You could get a brickie to cut those out, put in new ones, and then start again.

 

[^woody^]

Seeing as the grill almost covers the hole, couldn’t you install the vent pipe work then mortar well around it, let it cure then fix the vent in place? You wouldn’t see much of the mortar at all.... then you’ve got it cracked.

You're coming on nicely.

Have you put your quote in yet for that other air brick job? It will go towards all that plasterboard.

 

[pilsbury]

You're coming on nicely.

I’m assuming you’re referring to my eagle eyed wit rather than my skilful building advice.

 

[John D v2.0]

While we're on the subject of bodges, I blasted through our solid wall for a 150mm vent, but the wall is built with lime mortar in other words the same thing as a dried out and castle.
Anyway it's amazing what you can do with some external silicone sealant. Brown in your case.

 

[noseall]

some external silicone sealant. Brown in your case.

My thoughts too. I would be thinking about lining the whole cercumfrence of the hole and the plastic insert with brown silicone and pushing the fitting into a snug mass of the stuff. Then wipe off the excess. You can remove the louvres first and get a nice finish internally.

 

[tomfe]

We could do with some more pictures of the problem.
Also does not look like a 720mm hole to me

Anyone else would just gun loads of silicone in it and be off down the pub.

 

[SirLancelot]

I appreciate the contributions here - I am moderately competent at DIY. The hole was the correct size as according to the Manrose Kit instructions.

Don't fancy having the bricks knocked out and hole re-drilled. If I've understood correctly - members are suggesting that it's better to make good with the right repair material (once someone helps guide me to the right product).

If I were to 'make good' with some sort of cement/mortar - precisely what product I should be using?

Would normal Cement Suffice? Should I be using Mortar instead? Waterproof? What is the correct repair product to rebuild the edges of the hole for the sake of a long term solution.

Would any of these be right: http://www.u-can.tv/products-category/outdoors/

Or - is it still better to put wood/pvc square over it and go that way?

My sincere thanks to all those that choose to contribute.

 

[Bilabong007]

Mortar is sand and cement. Cement on its own is no use as it binds the sand together. If you haven't used it before it could get messy and highlight the area.

If it were me I would use an exterior grade silicone as suggested above. You can get it in brown.

Fix the vent in place and fill the gaps with silicone taking your time and smoothing it off with either a wet finger or a profiling tool. (What noseall said is even better)

Good luck

Graeme
Eta this stuff would do it
https://www.screwfix.com/p/no-nonsense-builders-silicone-brown-310ml/24384

 

[pilsbury]

Silicone fine. Personal preference. I’d go the mortar route. 4:1 building sand:cement. Not much water, nice stiff mix. Push it in nice and tight but without distorting your pipe otherwise you won’t get your vent in.

 

[pete50]

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.