I'm nearing the end of my garage rebuild and need advice on various aspects as I'm largely clueless about them and have done a ton of research but in a loop of contradictory info.
For background, I had a 1930s detached garage that was damp and dangerous as the walls were bowing outwards, plus cracks were opening on both long walls due to the slope and lack of foundations. I've had it knocked down, but due to its location on our property it had to be rebuilt to the same size and shape or it would have needed full planning permission and a pre-application visit made it clear it would be a nightmare to get through.
The double-pitched roof was completed this week, and the builders only have some rendering to finish off and the doors to fit and we'll be left with a new garage to use. The inside is up to me to sort, and that's where i'm having problems making decisions. The garage is approx. 7.2m long and 2.7m wide (external), with walls made of single skin block. It is divided into 2 sections internally:
One is approx 1.8m x 2.5m (internal), with a single door into the garden and no window. East wall is a party wall with neighbour's garage and has a pier to support the roof ridge beam. Consumer unit is also on this wall, which we had fitted 3 or 4 years ago. This will be my wife's section, used for gardening tools, washing supplies, kids toys etc.
The other is approx. 5m x 2.5m (internal), with a door into the garden and another door into the lane, the latter being a 1100 width door to get my motorbike in and out. There's no up and over door, but there's a 1.5 x 0.9 window on the garden-side wall. Internally there are piers next to each door, and another on the end wall to support the ridge. Slab is new, with a new DPC underneath. This is nominally my area, and when we contracted the builders the plan was just for it to be for my bike and general garage storage/small working area for a vice/airbrush etc., so we didn't consider insulating it.
Since the build started, my wife decided she'd quite like my 3D printers to be moved from the dining room into the garage, which is fair enough, but they are quite cold/draft sensitive so having bare block walls and no insulation feels like it's going to be completely unsuitable. I've also realised that if my printers are going into the garage, I'll be spending a lot of time out there too, and so might as well invest in kitting it out a bit into a small workshop for general DIY work, bike maintenance, model painting etc.
I've been looking at how to insulate it and due to the piers I had decided to build insulated frames so in cross-section would be "external blocks, 50mm airgap, 50mm insulation, vapour barrier, 18mm OSB". However, I've since read various threads on this forum and others which suggests this plan might not be the best as I'm not sure the new roof has much ventilation. It has ridge tiles for air to leave, but no soffits under the eaves for air to get in, just slate against felt on the fascia board edge. In this configuration, would air gaps behind insulation be pointless or even damaging with no air flow to remove moist air? The door is also going to be opened twice a day most days, and will have a dripping wet bike parked in it if it's been raining coming home from work.
So, question 1: what's the best way to insulate and maintain as dry an interior as possible this with the limited roof ventilation, or am I fighting a losing battle while the bike is inside?
The next area i'm unsure on is the external finish. It's being rendered with sand and cement, and i'd planned to paint it to match the house, but we do get a fair bit of graffiti around here and it would **** me off after spending a load of money on paint if someone tagged it. I'm now looking at using a breathable waterproofer for the render, like SmartSeal Brick Sealer, or Climashield, as they sell themselves as being anti-graffiti too.
Question 2 is therefore: does this sound reasonable for the external walls to give the best solution for keeping the inside warm and dry, whilst shrugging off spray paint?
The next area is the DPC, as it is not 150mm above ground height. We're still working on how best to sort it, but if we can squeeze 80mm height then we'll have done well. With that in mind, the plan is currently to have a french drain installed externally along the wall to try and reduce the opportunity for water to pool and soak into the wall at that point. I'm also intending to paint Black Jack on the internal wall/floor corner to a minimum of 150mm on both surfaces, as i thought this would double-up in function as i could then sit insulation/wooden frame on it.
Question 3: do these sound like reasonable mitigations to keep the floor dry?
The final area I'd love some input on is power. We have a consumer unit fitted, but it's single phase and I can't afford to have 3 phase fitted. I'd like to be able to install various tools in the future, and don't want to be limited if possible.
Final question: Is there anything else I could do to maximise the tools I could use in the garage (16 amp circuit maybe?), or should I just get used to only looking at single phase tools or fitting invertors/convertors?
As you can see, there's a ton of things going on that I really am struggling to make decisions on, so I'd appreciate any input on these aspects, plus anything else people can suggest that I probably haven't considered.
For background, I had a 1930s detached garage that was damp and dangerous as the walls were bowing outwards, plus cracks were opening on both long walls due to the slope and lack of foundations. I've had it knocked down, but due to its location on our property it had to be rebuilt to the same size and shape or it would have needed full planning permission and a pre-application visit made it clear it would be a nightmare to get through.
The double-pitched roof was completed this week, and the builders only have some rendering to finish off and the doors to fit and we'll be left with a new garage to use. The inside is up to me to sort, and that's where i'm having problems making decisions. The garage is approx. 7.2m long and 2.7m wide (external), with walls made of single skin block. It is divided into 2 sections internally:
One is approx 1.8m x 2.5m (internal), with a single door into the garden and no window. East wall is a party wall with neighbour's garage and has a pier to support the roof ridge beam. Consumer unit is also on this wall, which we had fitted 3 or 4 years ago. This will be my wife's section, used for gardening tools, washing supplies, kids toys etc.
The other is approx. 5m x 2.5m (internal), with a door into the garden and another door into the lane, the latter being a 1100 width door to get my motorbike in and out. There's no up and over door, but there's a 1.5 x 0.9 window on the garden-side wall. Internally there are piers next to each door, and another on the end wall to support the ridge. Slab is new, with a new DPC underneath. This is nominally my area, and when we contracted the builders the plan was just for it to be for my bike and general garage storage/small working area for a vice/airbrush etc., so we didn't consider insulating it.
Since the build started, my wife decided she'd quite like my 3D printers to be moved from the dining room into the garage, which is fair enough, but they are quite cold/draft sensitive so having bare block walls and no insulation feels like it's going to be completely unsuitable. I've also realised that if my printers are going into the garage, I'll be spending a lot of time out there too, and so might as well invest in kitting it out a bit into a small workshop for general DIY work, bike maintenance, model painting etc.
I've been looking at how to insulate it and due to the piers I had decided to build insulated frames so in cross-section would be "external blocks, 50mm airgap, 50mm insulation, vapour barrier, 18mm OSB". However, I've since read various threads on this forum and others which suggests this plan might not be the best as I'm not sure the new roof has much ventilation. It has ridge tiles for air to leave, but no soffits under the eaves for air to get in, just slate against felt on the fascia board edge. In this configuration, would air gaps behind insulation be pointless or even damaging with no air flow to remove moist air? The door is also going to be opened twice a day most days, and will have a dripping wet bike parked in it if it's been raining coming home from work.
So, question 1: what's the best way to insulate and maintain as dry an interior as possible this with the limited roof ventilation, or am I fighting a losing battle while the bike is inside?
The next area i'm unsure on is the external finish. It's being rendered with sand and cement, and i'd planned to paint it to match the house, but we do get a fair bit of graffiti around here and it would **** me off after spending a load of money on paint if someone tagged it. I'm now looking at using a breathable waterproofer for the render, like SmartSeal Brick Sealer, or Climashield, as they sell themselves as being anti-graffiti too.
Question 2 is therefore: does this sound reasonable for the external walls to give the best solution for keeping the inside warm and dry, whilst shrugging off spray paint?
The next area is the DPC, as it is not 150mm above ground height. We're still working on how best to sort it, but if we can squeeze 80mm height then we'll have done well. With that in mind, the plan is currently to have a french drain installed externally along the wall to try and reduce the opportunity for water to pool and soak into the wall at that point. I'm also intending to paint Black Jack on the internal wall/floor corner to a minimum of 150mm on both surfaces, as i thought this would double-up in function as i could then sit insulation/wooden frame on it.
Question 3: do these sound like reasonable mitigations to keep the floor dry?
The final area I'd love some input on is power. We have a consumer unit fitted, but it's single phase and I can't afford to have 3 phase fitted. I'd like to be able to install various tools in the future, and don't want to be limited if possible.
Final question: Is there anything else I could do to maximise the tools I could use in the garage (16 amp circuit maybe?), or should I just get used to only looking at single phase tools or fitting invertors/convertors?
As you can see, there's a ton of things going on that I really am struggling to make decisions on, so I'd appreciate any input on these aspects, plus anything else people can suggest that I probably haven't considered.
. Be careful - once something is knocked down, it no longer exists. Any new building requires exactly the same PP as it would if it was built on virgin ground.