Saul

I feel like the 1 part of the 1 to 6 was optimistic as it really does fall apart like a sand castle with very little agitation. A crack has appeared along the entire side elevation. I’m sure they’ll pass it off as just in the render and part of the process with a newly built property but I’m expecting to see more signs of instability given what the exterior wall is standing on. Photos of the block work internally show that the mortar is grey in colour so it’s just this DPC course of bricks that were laid a short time before the block work was done. Still waiting for the contractor to attend to inspect/carry out their own (“witnessed”) tests. Very stressful!

I thought building regs were 1:3. Their test will apparently be witnessed but I still need to ensure the sample taken is the one that makes it to the lab. But yes whatever the technical mix it clearly isn’t doing its job. The DPC was laid in April and I’ve been in 3 months. When it rains and bounces back up at the mortar it gets visibly wet and holds the moisture and then as it dries it sheds sand like in this photo. I sweep it away and then there’s more after the next rainfall. This gradual erosion is on top of the chunks falling out like in the vertical gap shown in original post. Hopefully they’ll agree to rake out and repoint. The DPC membrane is also recessed 25mm in several places. They scraped out some mortar for a small section and added a thin strip of membrane but watched them and it looked like a right bodge. The retaining wall behind the house was done with engineering bricks and grey mortar and is solid but that was a different contractor.

Posted about this before but now extremely concerned so would appreciate comments / advice. My house is built on a Piled Slab with Rendered Block Work. The Damp Proof course of S2F2 Bricks have been laid using 1:6 mortar as confirmed by Independent Professional UKAS certified Lab Report. To be honest you don’t need a lab report as the mortar is washing out every time it rains and if you tickle it with a screwdriver it falls apart like a sand castle on Margate Beach. The side elevations have stronger mortar in places so clearly different batches but the majority of the front and rear are extremely sandy. (Also a side note, not sure why the front protruding pillars are not sitting on the concrete base but appear to have some kind of pad stone below them. The house was signed off by building control and has a 8 year Protek warranty that kicks in after the builders 2 year warranty. They are being very slow to act and insist this is 1:3 mortar but it very clearly is not. I’ve been asked not to contact my house insurance, mortgage provider or warranty provider until they have conducted their own tests. I’m very worried the house has the structural integrity of a Kit Kat and that it will be condemned and need bulldozing and rebuilding. Cheers Saul

it wasn't my architect and didn't think you'd need one for a simple garage. Have now got a designer working on it which is costing £600 that I'd hoped not to spend.

I didn’t draw the upstands. They would border around the front and sides 150m above the top of the front ferring but the back will be open to the gutter. Proper drawings are being done. This is just me playing on Sketchup.

architect says that the eaves height of a flat roof is measured at top of roof, ignoring the parapet which would sit above the top of the roof from the Government Website http://data.parliament.uk/DepositedPapers/Files/DEP2012-1435/Parapets.pdf For the purpose of measuring height, the eaves of a house are the point where the lowest point of a roof slope, or a flat roof, meets the outside wall. The height of the eaves will be measured from the ground level at the base of the external wall of the extension to the point where the external wall would meet (if projected upwards) the upper surface of the roof slope. Parapet walls and overhanging parts of eaves should not be included in any calculation of eaves height.

architect says that the eaves height of a flat roof is measured at top of roof, ignoring the parapet which would sit above the top of the roof

Upstand requirements for flat roof design IKO TEAM 09/01/2022 A frequently posed question when designing flat roofs is “What upstand height do I need?” On the face of it a simple question with, one may think, a simple answer. Most of the time the simple answer is “150mm above the finished roof level”. We may give that advice but unless we probe further can we be sure that the advice is fully understood and correctly interpreted? In our experience, not always. BS 6229:2003 ‘Flat roofs with continuously supported coverings Code of Practice’ and BS 8217:2005‘Reinforced bitumen membranes for roofing Code of Practice’ both state that if unwanted water ingress into the building is to be avoided all weatherproofing upstands occurring around the roof area; (which would include abutments, rooflights and service vents etc) must have a minimum height of 150mm.

I forgot the 240mm I Joists from the list summary. The joists will run Side to Side so no need for a Steel. The door mounts to the face of the pillars inside. The Door is 2000mm tall but the running gear internally will be 140mm over the height of the door. Apparently the upstands don’t count as Roof Height so I should be able to do this in PD at 1m boundary.

Would love to get advice & thoughts on how a serious issue might be appropriately resolved. Lab tests have just confirmed that M4 mortar has been used below DPC on my house. Further to this it appears the DPC Membrane has been laid quite far back ie it is recessed from the face by about 25mm. This will presumably cause bridging, especially with the sandy M4 mortar and therefore result in rising damp. The DPC has been laid in rough face bricks rather than engineered bricks but they are classed as S2 F2. Feeling anxious and worried. The house is rendered Block above DPC. Thank you

Looking for any final advice before I move forward! Thank you! I’ve now moved in and need to get this garage built asap. It’s looking like it’s going to cost £35k all in which is still a massive amount of money. My issue is now with the internal ceiling height I’m like to get being 6’2” tall and thinking internally it’s going to be under 7’ To get this garage built within permitted development I will be GIA under 30m2. Garage Width will be 5.5m and Length 5.8m Externally. Block Built with Piers and Rendered to match the house. Maximum height under PD is 2.5m. The Double door will be 4500mm wide by 2000mm tall so I only have 500mm left!! The Headroom needed for the Door is 140mm. For the flat roof I need at least 240mm tall I Joists for the width span plus I need Ferrings and then a Stand Up 2500mm Max Height 2000mm Door Height 140mm Door Mechanism Head Room 78mm Ferrings Height 150mm Stand Up I’m over already by 88mm This is crazy!

Will do though not sure I can manage the weight of 5.83m long standard wood joists. I'll most likely go standard I Joist and Ferrings. Not seen anyone sitting I Joists on top of the block work or if they have how these would be secured to the blockwork...perhaps upside hangers. The house has Web Joists sitting on hangers within the walls but don't want to do this for the garage as would need another row of blocks and not keen on that design for something that doesn't have a floor above it.

Presumably you would add one firring per joist. Just found a site where they are £3.25 per m up to 6m. For my build with 5.83m this would mean 15 x 5.83 x 3.25 = £285. 2 rows of bricks on one side of garage would be around £50 excluding laying labour. I don't like the idea of offset walls but don't know why that wouldn't work unless there is a stress issue on the I Joists from not being square if they were ever subject to heavy load from snow etc. At the same time at the high end of the firring ie 150mm above Joist I'd prefer to know that the OSB was attached to the joist where in reality it will be nailed to the Firring which will be nailed to the Joist. The wall ties won't offer any protection against wind strain. Who would have imagined that 3 walls, a floor, a roof and a door could be so involved!

Thanks. I've pretty much abandoned the idea of a gutter at the back of the garage. As clean as that would be I'm not putting a steel across a door gap that wide as it will be super expensive. The issue with a 5.83m Firring is that it would be approx 150mm down to Zero. I just feel that those would be impossible to cut consistently.

I have read all the previous chains on flat roofs and know pitch angle and methods has been covered to some extent already but trying to wrap my head around why you would use Firrings as shown in the first picture when you could just create I Joists that have a slope manufactured within them ie by cutting the OSB Web such the bottom edge is flat and the top edge is sloped. In effect the I Joist would then have one end being 450mm tall and the other 300mm tall overall. (I know in the below example I have run Firrings front to back. If I used them this is what I would do as would rather have the gutter at the back) As well as custom angled I Joists I know I could also build up one side wall to be taller by adding a row of 2 bricks which would achieve the same fall off with guttering placed on the side of the garage rather than the back. I just don't like the gaps that this creates and think an angled I Joist allows everything to be nailed together square. As this is a single skin 100mm Block 7.3 build with Piers and no heating it won't be insulated and will simply have an 18mm OSB roof with EPDM Rubber, Fascias and Guttering. STS board will be attached the timber work and the sides will be rendered. Roller/Double Door. Appreciate any comments. Ultimately I need to build this as cheaply as possible as people seem to think £45k for a double garage is normal. I want to achieve this for max £20k in total including base finished and ready to store my classic car. Cheers Saul