To avoid these ads, REGISTER NOW!

Need help designing garage footing

Stoney85

Member
Joined
Jan 19, 2015
Messages
23
Location
NSW, Australia
The house I live in currently doesn't have a shed/garage..... I know, I know, how have I managed so far? moments silence for my pain.

The reason behind this is that the 2 story house is built on a steep block, 3,000m2 though, and there is no flat ground to build a garage, the block is pretty much useless except for trees and wildlife, and my resident pet kookaburras.

I've had enough! I cant see this being a cheap exercise at all, but the other option of selling up and moving will cost just as much in fees etc as building this shed, plus this will add value to the property anyway, as well as finding a nice place with some flat land and a shed locally is near impossible, justifying it to myself mainly.

I'll take some photos of what I have to work with this arvo, but i'm looking at peoples ideas on how I'd go about designing/engineering a flat area, level with the carport, capable of supporting a cement slab. The shed size i'm looking at is about 12m wide by 9-10m deep, reason behind this size is that I have quite a few 1960 Jaguars in various stages of restoration, I plan on having a hoist/lift in their as well.

Its hard to describe without pics, but behind the carport the land angles off meaning if I was to build a shed, the back side would need support poles or a retaining wall with a lot of landfill to create a flat space to have a garage that is the same height as the carport and initial area around the house.

Another option I was thinking about is half fill and then use a shipping container as the other half of the floor structure for a usable space under the garage for mowers, garden tools etc, what I'm unsure about though is while I know containers can support a lot of weight on their structural points, what process would I go about so it could support half a cement slab?

Or do I forgo the container, build a retaining wall with fill half way into the slab, and utilise the other half with support poles and a cement floor for open storage? The reason I'm not considering full landfill is because access to behind the house is limited to smaller vehicles, so no tipper trucks could get dirt there easily, and the retaining wall at the back of the shed would probably have to be at least 3metres high, so that's a lot of fill.

Here is my masterpiece courtesy of MS Paint, to at least give you some sort of idea what I'm rambling on about.

Throw me your ideas, as this is just a few I've come up with whilst on the verandah watching the sunset of an afternoon, pondering.
 

Attachments

  • Shed.jpg
    Shed.jpg
    9.1 KB · Views: 55
To avoid these ads, REGISTER NOW!

Jlbc212

Well-known member
Joined
Dec 7, 2013
Messages
1,530
Location
Northeast MA
Why not excavate into the slope? That's what I did. The concrete walls inside my garage are approx. 7 feet tall. My floor to ceiling height is just over 12 feet to accommodate a lift. Here's a picture of my house and garage. You can see the difference in elevation between the two.
 

Attachments

  • image.jpg
    image.jpg
    143.8 KB · Views: 36
OP
S

Stoney85

Member
Joined
Jan 19, 2015
Messages
23
Location
NSW, Australia
I have considered that as another option, but keeping the shed the same height as the carport is a must, there isn't any other access to the shed other than through the carport, and if its on a lower level, the ramp to the shed would be tight.

Photos of the place will give a clearer understanding of placement, boundary limitations and shed access.
 

Jlbc212

Well-known member
Joined
Dec 7, 2013
Messages
1,530
Location
Northeast MA
Relatively new building requirements for houses located along the ocean specify that the house sits above the mean sea level. This is done by placing the structure on concrete or wood pilings. You have a similar design issue. Pilings are driven down into the ground (at the beach - down to the bedrock) with a pile driver or can be poured in place concrete. You should consult with a structural engineer. You will probably need a design for the piles or poles and for a suspended concrete deck. This is not unusual.
 

bczygan

Well-known member
Joined
Nov 4, 2009
Messages
22,002
Location
DETROIT! Arsenal of Scrappers
The house I live in currently doesn't have a shed/garage..... I know, I know, how have I managed so far? moments silence for my pain.

The reason behind this is that the 2 story house is built on a steep block, 3,000m2 though, and there is no flat ground to build a garage, the block is pretty much useless except for trees and wildlife, and my resident pet kookaburras.

I've had enough! I cant see this being a cheap exercise at all, but the other option of selling up and moving will cost just as much in fees etc as building this shed, plus this will add value to the property anyway, as well as finding a nice place with some flat land and a shed locally is near impossible, justifying it to myself mainly.

I'll take some photos of what I have to work with this arvo, but i'm looking at peoples ideas on how I'd go about designing/engineering a flat area, level with the carport, capable of supporting a cement slab. The shed size i'm looking at is about 12m wide by 9-10m deep, reason behind this size is that I have quite a few 1960 Jaguars in various stages of restoration, I plan on having a hoist/lift in their as well.

Its hard to describe without pics, but behind the carport the land angles off meaning if I was to build a shed, the back side would need support poles or a retaining wall with a lot of landfill to create a flat space to have a garage that is the same height as the carport and initial area around the house.

Another option I was thinking about is half fill and then use a shipping container as the other half of the floor structure for a usable space under the garage for mowers, garden tools etc, what I'm unsure about though is while I know containers can support a lot of weight on their structural points, what process would I go about so it could support half a cement slab?

Or do I forgo the container, build a retaining wall with fill half way into the slab, and utilise the other half with support poles and a cement floor for open storage? The reason I'm not considering full landfill is because access to behind the house is limited to smaller vehicles, so no tipper trucks could get dirt there easily, and the retaining wall at the back of the shed would probably have to be at least 3metres high, so that's a lot of fill.

Here is my masterpiece courtesy of MS Paint, to at least give you some sort of idea what I'm rambling on about.

Throw me your ideas, as this is just a few I've come up with whilst on the verandah watching the sunset of an afternoon, pondering.

I see in your drawing, that you have balanced your cut and fill. That is good, if the excavated material is suitable to use as the fill material.

Frankly, if you can use the extra space, I would cut under the entire garage. I don;t like a slab going from one type of support to another. It always cracks there and differential settlement will create a step. And remember that everything settles.

So build the basement portion out of reinforced concrete or concrete block with reinforcing as required for the different conditions. Then install pre-stressed reinforced concrete slabs on top for a floor for the garage. Then frame out the garage.

Easy-peasy, but not cheapy-weapy.
 

sideroad

Well-known member
Joined
Dec 9, 2013
Messages
84
Location
Goodna Queensland Australia
Hey Stoney85, I followed you from your post on my thread (which is overdue for an update).
What is your budget?
Are you planing on doing all the work yourself?
Do you have the skills/ability/time to do the work yourself?
Do you have aesthetic requirements or is it just a shed?
I know you want full concrete, but does it need to be concrete all the way to the end?
A 3/4 concrete slab is do-able and the last 1/4 could be 18mm (or thicker) compressed concrete flooring. This would still allow welding, jacking and general use and keep the cost down, also would allow for a storage area under.
With the correct design/engineering you could even have your hoist on FC (fibre cement) flooring and have a 1/2 concrete and 1/2 FC floor.
I did look into a suspended concrete slab on steel columns for my build and it could have been done, but the cost would have been at least $30k extra. So no go.
I would have gone from a hand build to a hired trade and machine build. Excavators, cranes etc.
If going posts I would absolutely recommend the sure foot (http://surefootfootings.com.au/)method, or screw pile footings if you have machinery access.
The container idea is a good one. The roof of the container would be supported with props for the pour and about a month after and then could be removed.
If using the container I would be concerned with rust.
I would make sure that it was not in contact with the soil or any sitting water. I have a container at my folks block that has serious rust issues underneath (not directly touching the soil) and that is just from the rising condensation from the soil.
 
To avoid these ads, REGISTER NOW!

sideroad

Well-known member
Joined
Dec 9, 2013
Messages
84
Location
Goodna Queensland Australia
If going concrete all the way to the back you may need to go with a steel posts and bracing and precast concrete beams with an infill insitu slab.
http://www.ultrafloor.com.au/SiteFiles/ultrafloorcomau/Metal_Deck_Typ_sections_A.jpg

If you did go down the line of FC flooring, you could tile the floor with industrial grade tiles similar to car workshops/dealers in europe (same tiles used in ALDI foodstores) as they are fine with jacking on and forklifts. They can also take pretty heavy abuse.
Have a look at this thread (warning, it is very long, I am only 20% through it so far)
Jack uses tiles and seems happy with them.
http://www.garagejournal.com/forum/showthread.php?t=55006
 

sideroad

Well-known member
Joined
Dec 9, 2013
Messages
84
Location
Goodna Queensland Australia
So build the basement portion out of reinforced concrete or concrete block with reinforcing as required for the different conditions. Then install pre-stressed reinforced concrete slabs on top for a floor for the garage. Then frame out the garage.
This clearly a great option if budget allows. (slab could be insitu pour also) Huge usable lower rooms with consistent temperature, great floor slab to work off.
Would be awesome if you can afford it.
A short cut could be excavator driven screw piers with concrete beam perimeter and internal footings and core filled blocks for the walls and internal supporting walls. This would remove the need to cut the hill, but still give you the slab.
Building on the hill will involve deep footings to stop it moving down hill with ground movement.
 
OP
S

Stoney85

Member
Joined
Jan 19, 2015
Messages
23
Location
NSW, Australia
So many great ideas.

I think a first call will be to get an engineer in for their opinion on structural loads etc and what can and cannot be done.

While I'd love to throw bulk cash at it to be done, being a mechanic myself (you can see why I want a decent shed) I can see myself doing a lot of the installation and form work etc, which I'd enjoy anyway.
 

sideroad

Well-known member
Joined
Dec 9, 2013
Messages
84
Location
Goodna Queensland Australia
Before getting an engineer involved, I would be locking in a budget. No point in paying for engineering services and then changing direction and having to start from scratch.
I'm sure there are online calculators that will work out the loads and required concrete.
 
To avoid these ads, REGISTER NOW!
Top Bottom