House Renovation - Sun Room

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Renovating a house from top to bottom, part of which is the partial rebuild of a Sun Lounge. I'm a rank amateur at this game, and have learnt enormously from having to go through pain, so I'm jotting this down in case it may help others. Apologies to anyone (and there must be very many) at a greater skill level than me.

Please feel free to add comments, correct errors etc. I hasten to add that this is a narrative of my experience - my learning curve. I am in no way shape or form a builder ( as will become apparent!) and there are far better skilled folks on this forum from whom to seek advice and help.
Anything I put here is what I have seen, or been told, or advised.


The difference between a conservatory and a sun lounge is that a sun lounge has a solid roof (thanks Local Authority Building Control LABC).
As such, it needed Planning Permission and inspection with respect to Building Regs. It was built in 1970, and was inspected at Excavation For Foundations, Foundations and Damp Proof Course, but interestingly enough not after! This didn't come up in the searches carried out prior to purchasing, but through my own searching at the council offices. Buyer Beware!
Sun lounge construction is interesting, in that there is a brick outer skin, block inner skin and a small cavity. Roof joists go the length of the lounge, rather than the shorter width. Thus, the supporting walls are the ones at the side of the lounge, rather than the one that contains the patio doors. Also, two very large wooden lintels are installed across the two supporting walls, covering the gap over the patio doors. Well, sort of!
In fact, the two wooden lintels, enormous and strong though they may be, support half a dozen lightweight blocks. The outer skin of brickwork is supported by the patio door frame!
Needless to say, the brickwork has failed, and needs replacing.

I have placed a Building Notice with the LABC, and paid the relevant fee. They have, to date, been extremely helpful answering my dim questions.
So I'm now ready to make a start.

I've taken away most of the brickwork, leaving a stub in the corner which helps hold up the roof (the outer-most joist rests on the brickwork too), having accrowed up the joists. Since the joists are not supported by the wall that I am removing, you may well ask why I bother with accrows. I do this because blokes that know what they are doing told me to do this. When I know what I'm doing, I might argue then, but not before!
Took the bricks out one by one by removing one or two from the top course, and then checking the accrows for any problems. Bosch Rotary drill justified the £90 I spent on it !

Now the planning for the replacement wall. This is an old property, so I've now spent a lot of time waiting for brickies and builders to tell me that I won't be able to match up the bricks and the courses because the bricks are impossible to get, and impossible to match for size. So it is impossible to have a brick outer skin that will look good. Since a number of them have said this, I now believe them. Lots of time lost though.
Only viable option is to rebuild the wall, then render and pebbledash. Should look OK.

Having planned the new doors, and triple-checked the size of the hole required to fit them, it's time to sort out the details.
LABC tell me that:
- I can use blocks if I'm going to render afterwards. External must be Class A, or 7 newton blocks. I learn that this is a measure of the density of the block.They are quite heavy too! 3.5 newton blocks are fine for the internal skin or leaf (wall to us non-brickies!). I chose 4newton thermalites.
- If I'm adding to an existing wall, then I can continue whatever cavity (or absence of cavity) currently exists. If I'm building a new wall, then it has to be cavity, and 70mm.
- Lintel choice then simplifies (have you seen how many different types sizes shapes ?). I need a cavity wall lintel, 300mm longer than the hole for the doors, since the lintel needs 150mm either side resting on the wall.
- They only need to inspect once the wall has been built, and before it has been plastered (so they can check on the presence and state of the lintel and cavity I guess). They also say that they will try to get out same-day if I call early enough in the morning.

I've discovered a number of things, mostly from this site, which I list now.
- cavity wall is filled with insulation batts
- the cavity must now be closed with cavity Closers, rather than simply putting a brick or block in the gap. This is to avoid thermal bridging, which reduces the effectiveness of the cavity.
- wall starters can be used to "key" the new wall into existing ones. These are strips of metal that are firmly screwed into the existing wall, and offer tags upon which the new wall can be started. Removes the need to remove bricks in the existing wall (toothing)
- I've had loads of conflicting advice from well-meaning folks. Get a brickie and a builder that you trust, talk it over with them and then check with the Building Control Officer (BCO).
- The technical support lines for manufacturers (eg Catnic for lintels) are very helpful, and give the sort of help and advice sometimes lacking at the Builders Merchants.
- metal ties are used to hold the two skins/walls together. This have a particular shape to stop moisture travelling across them. Should these ties get dirty (mortar etc) then the moisture may flow from external to internal wall, and thereby into your nice clean (expensive) plaster.

Next stage is to call my BCO to check a few assumptions I've made or had made for me, and also to check up on whether it is necessary to:
- put a Damp-Proof Membrane (DPM) between the cavity closer and the external wall
- put a DPM under the frame of the new doors (which will sit on the Damp Proof Course DPC)
- use Lintel End-Stops. These apparently ensure that any water that finds its way in across or onto the lintel, is dealt with.
- how many courses of engineering bricks (blues) are required (hopefully only 2)
- and of course "Is there anything that I've missed?"

Update tomorrow hopefully!
 
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Thanks for your post. Your BCo must be a lot friendlier than mine as when I asked him about the wall construction he didn't mention 7 newton blocks were required. Thankfully I went for them on purely a gut feeling. I was going to use Wickes concrete blocks throughout! Well you did well in finding out that 4newton blocks ware ok for the inside. I used 7newtons for both inside and outside! looks like I could have saved some cash for the inner leaf.
Btw can you post some details on the cavity closers as i will be reaching that point soon.
Thanks
 
Update:


Picture 1
Picture 2
Picture 3

Picture 4

Another chat with the BCO turns out to be very helpful. They tell me that
- Cavity closers are now a must (for this LABC)
- DPC must be laid on the blues (I thought the row(s) of engineering bricks constituted the Damp Proof Course. I'm told now that, because damp can seep upwards through the mortar a sheet of plastic material known as Damp Proof Course needs to be laid upon the blues)
- inspection is due on completion of building work, and before any plastering/rendering is done. Inspection will be done only on items mentioned in the Building Notice (apparently). Which means minimal checking will be done on the replacement cavity wall I'm building, since it is classed as minor repair/maintenance (which I'm not going to argue with).

Having laid several course of the blocks, I've discovered a few things:
- brickies and builders have huge forearms. This is no coincidence. The 7newton blocks weigh a ton !
- the Lite in ThermaLite is a relative term. These also weigh a bit after a while!
- a good way to cut the blocks is to obatin a 230mm 2.2Kw angle grinder, cut on both long faces to 10mm depth or so, and then batter with a bolster and lump hammer.
- its worth spending time getting the mortar bed level, since it's not so easy to move blocks around as bricks.
- if, like me, you're fitting patio doors, and therefore building a hole, and you have the luxury of already having the roof on, then hang a bit of 4x2 from the rafter/joist (or whatever the correct term is) vertically down at the point where the edge of the wall should be (ie where your doors are going),. Build to that wood, and use it to knock in the blocks - makes for a reasonably clean edge.
- I've found that you can impale your insulation batts on the brick ties, so my sequence is (1) exterior wall 6 courses (2) impale insulation batts (3) interior wall 6 courses
- using frogged bricks (bricks with a "valley" cut out of the top) is a good way of making the right height at the top of the wall, since the frogs are easily trimmed off to give a half-height brick. SO much easier than slicing a solid brick

So, weather permitting, tomorrow I'll be
- finishing the internal walls
- matching the heights (aggghhh)
- installing the lintel (by the way, that bit of polystyrene in the cavity of the lintel is NOT packing, and shouldn't be removed!).
- blocks in either side
- installation of closers

Hope this is of use to folks, it'll be a valuable aide-memoire to me in 3 months time, so my apologies for any boredom being caused out there!
 
Tony - I've found my LABC to be very friendly and helpful. They're just exceptionally busy a lot of the time.
I'll let you know about the closers, though I'm not anticipating problems with them (yup, ranks alongside "of course I'll marry you" I know!)
 
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Right ! Walls are up, and heights roughly matched. I've left them to settle and allow the mortar to go off before I fit the lintel tomorrow.

I omitted to mention that I'd asked the BCO if they required Stop Ends to be fitted to the lintels. He said to check with the manufacturer as to whether they were necessary (funny, sinec the book said that some LABCs are insisting, thereby suggesting that it was the LABC not the manufacturer that made the decision). In the end, the manufacturer's helpline said to line the ends with DPC and that'll do the trick.
My obvious question is: If the open ends of a lintel require sealing off to stop the ingress of water, then why are they manufactured open ?

Hey ho - the joys of being a rank amateur.
 
Slowly but surely!
Bit of repair work to be done to the existing walls to allow wall-starters to be used properly. Where there's only 2 or 3 courses to tie in, I'm using some 15mm wide bars, slotting them into the existing brickwork and the new mortar, to tie them in.
Lintel up and onto the part ricks put on top of the blocks, in order to level it all up. Bedded on a small bed of mortar, and left to go off for an hour or so. Blocks went on a treat across the lintel, only problem was getting the steps/scaffold plank at the right height to get those 7newtons up without killing myself!
Course of blocks on the inside leaf, to make sure the lintel is loaded on both sides, albeit somewhat unevenly.
Final course of bricks to put in for the exterior leaf tomorrow, followed by the last two courses for the interior (with associated insulation batts of course) and then it's time to fight with the patio door frames!
 
All the brickwork and blockwork now in. The fiddly last bits take a lot longer than you would think! Putting the last brick/block into the course is a lesson in patience, trying to keep the mortar on both sides of the final brick. Must be a technique for this...
Last bit of making good, where I had to cut into the existing brickwork. This was simply a 3-1 sand&cement mix, liberally plastered onto the brickwork ( which had been treated with a 5-1 UPVA glue mix).
Cavity closers were simple to fit. I removed the fillers, cut the plastic to size with a hacksaw, cut the fillers with a sharp blade, and in they went, sealed with a bead of silicone either side for weather-proofing. Time to leave the sand&cement to go off, before fitting the frame.
Frame is a proprietary Wickes French Door with side panels thing, fiddly connecting together and then standard drill it into the brickwork from what I can see, so unless anything remarkable happens this will be the last update until the dreaded BCO inspection!
 
Hmm..."seems to be progressing well" is doubtless the kiss of death ! :LOL:

I've requested of the moderators to lob of few photos in for your entertainment. Please not too much merriment at my amateur brickwork!
 
Picture 1
Picture 2
Picture 3
Picture 4


Picture 1 gives an overall idea of my little project. The blocks on the right as you look at it were a window, the brickwork below is original.
Picture 2 shows the cavity closer in place. Just noticed that the camera angle makes it look like the wall is about to fall down!
Picture 3 shows the lintel in all its magnificence. This will be filed for when the house is sold, as proof positive of its existence.

Frame's in (what a game), a very snug fit I'm proud to say. Doors on tomorrow, glass into the sidelights and then it's down the pub to celebrate!
Which means the inspection will be on Thursday. :eek:
 
I've requested one final photo from those awfully nice admin guys, just to show the finished article. The last thing to happen now will be the rendering and pebble-dashing, but since I'm not going to do that myself it seems a cheat to claim the credit!

Incidentally, the BCO came, checked the glass, chatted very briefly about what I had done, and off he went, after promising a Completion certficate in the post. I have popped my BCO Inspection cherry ! :LOL:
 

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