Building a new Conservatory

[Warwick_Tech]

Hi All,

I have taken the plunge and ordered a self-build conservatory

 

 

They make it look so easy!

 

Anyway; the only issue I have is I need some advice on actually attaching it to the house, and the flashing on the roof.

 

The house has render instead of plain brick and some of it has been applied thicker in some places than others (thickest difference is about 10mm)

 

But it's thick in a bulge around the middle (just to be difficult) so the conservatory would be attached like so: )]

 

Now, the question is do I;

 

A) Baton out the Conservatory on washers/wood where needed and seal somehow with foam/silicone/flex seal

PROS:

Easy, with no damage to external or internal walls - minimal structural change

Able to change washer sizes from 10mm all the way down to 1mm

 

CONS:

Base will need to be adjusted to compensate for the bulge

More likely to leak/rain damage to enter through cracks

Wouldn't be as aesthetically pleasing (large silicone beads on the side)

Will need to be precise with the base placement or else it will need to be adjusted

 

B) Grind off the render to make it smooth

PROS:

More solid fix to the side of the house, smaller gaps

Better structural integrity

no rotting wood, draughts etc.

 

CONS:

Dusty, dirty and potentially hazardous (flying bits of stone etc.)

Grinding too much may cause damage to the external brickwork allowing in moisture

Grinding the entire area is very time consuming

 

Bear in mind with this project I'm going to have to flash and grind anyway

 

(I'll be using lead alternative)

 

What do you all think?

 

Quick summary - Fixing a straight exterior wall to a wonky one, what's the best option?

 

Amazingly I have found 0 videos on YouTube that cover this!

[Warwick_Tech]

The only related video

 

 

So it works! maybe a little too well...

[jmak]

So a few things to note, if not a complete answer...

 

Are you certain you know what is under the render? The 3 phase power supply to my house was buried under the render behind the conservatory on our house. A builder found it with an angle grinder when he was replacing the flashing on our conservatory. The bang was very big. The bill was very big (builder's insurance paid). On the plus side, no one died. With the knowledge that there was a cable buried illegally, I saw a bulge in the render...

 

Expanding foam. As the man in the video experienced "it's called expanding foam for a reason"! Most people make a mess the first time they use it. Also, you do need it to expand beyond the hole you're trying to fill, otherwise there'll be gaps. Therefore there will be overspill. Mask the surfaces around the hole you're filling, then you can cut back to the level you need and won't end up with foam stuck around the hole looking messy. The foam will last indefinitely and is a good insulator, so there no problem using it to fill the gap. However, it can absorb water and then effectively leak, so you need to make sure it's covered with a weatherproof layer.

 

My advice on the fitting: I would batten out the top and the sides, fill the gaps with expanding foam and get some trim that matches the conservatory to cover the gaps at the side. Cut the trim to follow the contours of your house and leave a vertical line where it home the conservatory and it will look smart.

 

If the surface you attach to isn't perfectly square/flat, you're likely to twist the conservatory when you attach it, which will cause problems down the line - probably leaks. We had a replacement conservatory fitted last year, using the existing dwarf wall. It was a bit more complicated as we went for a flat roof with a lantern, but to give you an idea, it took them a week and they spent the first day and a half getting everything level. It was complicated because the wall wasn't level and it fits in the inside corner of an L shape of the building and the walls aren't at right angles to each other. Once they'd got a square surface, the rest went up in a couple of hours.

 

Hope that helps.

 

Edit: mikeprice style anecdote. A colleague had his 6 month old company car written off by a can of expanding foam. One was dropped on the road in front of him, exploded and covered the front of his car. It got inside suspension, brakes, radiator and covered the paintwork and insurance company said it wasn't worth repairing. It was 15 years ago and the car was £25k.

Edited December 9, 2020 by jmak

[Warwick_Tech]

Are you certain you know what is under the render? The 3 phase power supply to my house was buried under the render behind the conservatory on our house. A builder found it with an angle grinder when he was replacing the flashing on our conservatory. The bang was very big. The bill was very big (builder's insurance paid). On the plus side, no one died. With the knowledge that there was a cable buried illegally, I saw a bulge in the render...

 

Well this was a concern, but we've had all the electrics redone in the last 5 years (used to have the old fuse wire system) and it seems very unlikely any power goes through there (I can find the main in at the centre, along with the Earth wire) but definately worth a worry - I was also thinking damp course and plumbing, but TBH there should be very litte attached to that back wall

 

Expanding foam. As the man in the video experienced "it's called expanding foam for a reason"! Most people make a mess the first time they use it. Also, you do need it to expand beyond the hole you're trying to fill, otherwise there'll be gaps. Therefore there will be overspill. Mask the surfaces around the hole you're filling, then you can cut back to the level you need and won't end up with foam stuck around the hole looking messy. The foam will last indefinitely and is a good insulator, so there no problem using it to fill the gap. However, it can absorb water and then effectively leak, so you need to make sure it's covered with a weatherproof layer.

 

This is where I was hoping the flex-seal would come into play - Expanding foam, flex seal and some white masonry paint

(Phil, put the knife down)

 

But, I worry about the structural integrity with a foam gap between panels (obviously the screws would need to be deeper)

My advice on the fitting: I would batten out the top and the sides, fill the gaps with expanding foam and get some trim that matches the conservatory to cover the gaps at the side. Cut the trim to follow the contours of your house and leave a vertical line where it home the conservatory and it will look smart.

 

The trim was the hardest to find! I experimented with scribing but the pebbledash was too irregular for that

 

If the surface you attach to isn't perfectly square/flat, you're likely to twist the conservatory when you attach it, which will cause problems down the line - probably leaks. We had a replacement conservatory fitted last year, using the existing dwarf wall. It was a bit more complicated as we went for a flat roof with a lantern, but to give you an idea, it took them a week and they spent the first day and a half getting everything level. It was complicated because the wall wasn't level and it fits in the inside corner of an L shape of the building and the walls aren't at right angles to each other. Once they'd got a square surface, the rest went up in a couple of hours.

 

I was hoping this would be easy as the only wonky bit is the wall of the house (!)

 

Hope that helps.

 

Thanks for your input, most appreciated

[Simcfc73]

Personally I would grind the render off to the flat brick then just patch up any bits that fall off.

 

Sounds like a fun project, I'm itching to start a new one.

[jmak]

Well this was a concern, but we've had all the electrics redone in the last 5 years (used to have the old fuse wire system) and it seems very unlikely any power goes through there (I can find the main in at the centre, along with the Earth wire) but definately worth a worry - I was also thinking damp course and plumbing, but TBH there should be very litte attached to that back wall

 

 

 

This is where I was hoping the flex-seal would come into play - Expanding foam, flex seal and some white masonry paint

(Phil, put the knife down)

 

But, I worry about the structural integrity with a foam gap between panels (obviously the screws would need to be deeper)

 

 

The trim was the hardest to find! I experimented with scribing but the pebbledash was too irregular for that

 

 

 

I was hoping this would be easy as the only wonky bit is the wall of the house (!)

 

 

 

Thanks for your input, most appreciated

You're welcome. Quote function isn't working properly on my app so I can't break the answers down.

 

Flex seal looks good.

 

If you can't scribe, maybe you could grind a slot?

 

The expanding foam is definitely not structural. It'll fill a gap, but isn't suitable as a mounting surface.

 

I suggested battens at the side as I was assuming that if you batten at the top, you'll end up with gaps at the side. You could make wooden shims to put between the conservatory frame and the wall at the points where you attach it.

 

After all of the rest of my ideas... You could just grind out the deeper render at the top... It depends how much grinding you think it'll take. My instinct is that using battens would be easier; either will work. The key thing will definitely be getting it level.

 

The builders who fitted ours used shims like these for fine adjustments:

 

https://www.screwfix.com/p/broadfix-assorted-plastic-shims-medium-200-pcs/80408

Edited December 9, 2020 by jmak

[caffrey]

Yep, concrete screws and packers, foam the gap then use upvc plastic fillet trim to cover, then silicone

 

Best bet is just to cut out the channel, but make sure your render is solid else you could run into bigger issues

 

We should have a DIY Sticky for projects etc.

[Warwick_Tech]

Personally I would grind the render off to the flat brick then just patch up any bits that fall off.

 

Sounds like a fun project, I'm itching to start a new one.

 

I'm hoping it will be fun, otherwise I'm in trouble!

 

I suggested battens at the side as I was assuming that if you batten at the top, you'll end up with gaps at the side. You could make wooden shims to put between the conservatory frame and the wall at the points where you attach it.

 

This was my first idea, however I got stuck at the part of filling a 10mm gap between walls - Especially if they're around 2-3 inches thick (hence, squirt the foam in)

 

After all of the rest of my ideas... You could just grind out the deeper render at the top... It depends how much grinding you think it'll take. My instinct is that using battens would be easier; either will work. The key thing will definitely be getting it level.

 

Agreed, TBH I want to avoid grinding as I don't want to repair and not keen on creating dust storms of spikey stones

 

 

The builders who fitted ours used shims like these for fine adjustments:

 

https://www.screwfix.com/p/broadfix-...-200-pcs/80408

 

Those would do the trick, but again it's all about filling the gap between the walls.

 

Another idea I had was to create a wooden or PVC 'frame' that was perfectly level so I just attached the conservatory to that...

[Smed]

grind the render back to the brick/block, if you dont the rain will track through the render and show on the inside.

before you foam up any gaps, spray with a fine mist of water, this will stop the foam from falling out of any gaps and also allows it to expand properly. then as above just stick on some upvc trim the same as the frames with silicone, and silicone the gap from the trim to the render.

at the roofline I would personally grind lead into the render as a bare minimum, much better will be to install cavity trays, look above the door that will lead back into the house, are they any "weep holes" above the door? if so there is a possibility any rainwater will come through them if there is any problems above the conservatory.