MegaSack DRAW - This year's winner is user - rgwb
We will be in touch
The issue is that I dont want to go ahead with a structural engineer if I have to involve the highways as it will be silly expensive.. but I also dont want to pay a structural engineer £200 just to come and take a look!
I'm wanting to pop a window in a room that is below street level at the front of the house.
The inside of the wall that goes onto the street and borders my small yard is 2650mm away from the external front wall of the house.
I've roughly calculated that I need a hole 1600mm deep... how far back would the hole have to be dug assuming the ground was a mix of gravel and standard draining type looseness that would be infilled in front of a mid 90's house.
Thanks!
A camera at street level hooked up a TV mounted to the wall would be a lot cheaper an easier 😉
Roughly you say? Well roughly 45 degrees.
No warranty though.
Difficult to assess without photos, but for a rough initial calc, use the 45 degree rule. So for a 1.6m hole you need to be back a horizontal distance of 1.6m. You will have to allow for working space for the installation, etc. This is assuming you are going to batter back the excavation for the installation. This will also allow any loading at ground level to be transferred (45°) below excavation level.
Does this help or actual photos needed? I tried to show a side profile of what I'm wanting to achieve.
I know there is a 40mm steel / concrete retaining wall under my garden and against the building and I'm wanting to dig down and open up a well and then it'll probably be lined with reinforced block work and possibly concrete filled to allow a window to be added in the downstairs room.
Issues I'd say appear to be the depth of the walls foundations in the garden and how close this is coming to the pavement.
Basically I'd like to somehow get to a point so he doesn't just say "thanks for the £200, you'll need highways involvement though".
If it only goes back 1.6meters to go down 1.6 meters that sounds like I've got loads of space. I'm assuming i'll need to go back 2.2 meters tops.. hopefull thats not too encroaching on the garden wall either? is that a consideration or would that be propped against my building potentially?
A light bulb would be my solution. The view won't be great.
I would start digging a sample hole and see whats there..
when you have allowed for working space the garden wall will be in your basement.. to dig that deep 1.6m on any site i would have to leave min 600mm working space behind the wall then batter or step ( max 1000 vert depending on soil)then 1000 hz etc. could you use a 'light tube' or 2. How big is garden wall? not a struct eng btw
What are you hoping to achieve with this new window?
so if the garden wall is is 2650 away from the front of my house external wall then I have 2050mm of garden space to work with. Based on the 45 degree thing doesn't that still mean I'm fine though?
To make it officially a bedroom I believe it needs to have a window. Also as it's a 3 story building it's best if its fire escapable however possibly not mandatory but building control said they'd like to see it.
The garden wall is about 40cm wide and roughly a meter high above ground and im assuming its shallow into the ground
First and foremost how are you removing water when it's completed?
The new retaining wall for the well will be tanked and there is a drain running the length of the front of the properties under the garden to release the hydrostatic pressure so that is all the same so no extra drainage needed.. the drain will still be about 0.75 meters below the hole im creating
Ok that's that sorted. What's the ground like? We've had some mighty storms over the last week week or so and may main concern would be loss of ground regardless of angle of repose.
Do you need some sort of bars across the top to stop people falling in? Its a fairly standard thing on the street side of houses round here but lots of people also end up fitting some sort of perspex cover as they get fed up with all the leaves and crap that fall down. Still not a bad idea though.
Why don’t you ask highways whether it will require permission? If you were to get any sort of professional advice, my bet is regardless they would say you must check with highways.
Most likely you will need an AIP (approval in principal) from the highways agency. Resolving forces at 45 is a general rule of thumb, you should resolve at the angle of shearing resistance of the soil (phi = more likely to be around 30 to 30 degrees with a granular backfill).Water ingress could be a real problem as you have a granular backfill.
pay the guy £200.
And in reality you should be creating a proper retaining wall which would require an element of structural design. I know how I'd construct it but all the risk would be on my design and at the end of the day I'm not a qualified structural engineer....
If you end up with the pavement subsiding in any way they will bill you and bill you hard!
Just to be clear I'm not planning on doing this without a structural guy.. I just wanted to gauge if I can actually do what I want before spending £200 to just get a "no". From everything I've seen its likely I can do something but probably with a much shallower window to not involve anyone.
Leffe boy - its actually in my yard not on the pavement but yes it'd have a perspex top likely.
I'm going to call highways now - a good shout!