Browse Forums Building Standards; Getting It Right! 1 Nov 30, 2012 10:34 pm Hi, We have a design question that would really hope to hear some opinion about. I haven't worked out how to post an image yet so I will try to describe the block. We have a rectangular block that is lower than the street level. The block is sloping diagonally from the north-west to south-east corner, street is on the west. The fall of the building pocket from north-west to south-east is about 1.4M. We try to work with the landscape as much as possible in our design. Current we have rumpus, garage and main living areas on three separate floor levels on the ground floor. Rumpus on the north-west is 60cm higher than living areas on the east, and garage on the south-west is 30cm lower than rumpus, but 30cm higher than living areas. With these design there would be a cut of about 40cm on the front and fill to the far east of the block to raise the living area's floor level. Our architect has told us that in general it is not a very good idea to have garage floor higher than the main living area as garage is not seal and water can go into the main house through the garage. I can understand his point as the driveway is already sloping down from the main street to the garage and water can come in during a big storm if the drainage fail. There are two options, first is to lower the garage floor by 40cm so it becomes the lowest point of the house. The second option is to lower garage by 10cm and raise the living area by 30cm (that way we need to reduce our ceiling heigh by 30cm as well). We don't really want to lower the garage floor further as we already taken 40cm of soil from the garage already. If we are to lower the garage by another 40cm so that the garage become 10cm lower than the main living area, then the driveway will be very steep and much harder to stop water from going into the garage if there is a big storm. 10cm of buffer is not much to stop the water going into living area. The second option is sort of ok with us but still a bit unsure. That is because at the east of the house, we are filling about 70cm of soil there. We are not sure how good the concrete slab will be and how much more foundation and retaining work we need to have a concrete slab on a 70cm fill. Second is we now have a stair to go down 70cm to the backyard. I rather leave the garage floor where it is now, and then put a 30cm waterproof concreate wall between the garage and living area, and add a drain hole in the garage to get the water out if water ever comes in. My theory is that it is easier to prevent water coming in when the slope on driveway is not that steep, and 30cm of wall offer more buffer than a 10cm wall. The architect has no problem with it, but warn that there is a risk that if the water ever comes into the garage and the drain hole can't discharge the water fast enough, the water could soak through the concrete floor/wall to damage the living area's floor. The insurer might refuse to pay out in that case becaue of bad design. What is everyone's view about garage floor higher than living area? Thank you. Re: Question about garage and house floor level 2Dec 01, 2012 10:59 am We are also building on a downward sloping block, well we will actually start the build next year. Our garage sits approx 50cm higher as well. Ours is a side entry garage with a driveway that sweeps from left to right. Our architect has advised we put a strip drain in approx half way down the driveway to reduce the amount of water entering the strip down in front of the garage in the event of a downpour. They are also putting a drain in the floor at the bottom of the steps, just before the door to the house. I have no doubt that that will be more than enough. I've spoken to some of the neighbours on the street who have a similar fall of land and driveway as ours and they said they've never had any issues with flooding etc. Custom downslope build Build thread viewtopic.php?f=31&t=61873 Blog http://www.buildingroyalmanor.blogspot.com.au Re: Question about garage and house floor level 3Dec 02, 2012 7:00 am Thank you HomeAngels, I wasn't too worry about water coming into the house too. But then there is always a risk about those once in a hundred year type of storm. Even then I think having the 30cm concrete wall plus drain in the garage will be in a better position than the lower garage floor. (Our street is sloping down from north to south as well so the south of garage is lower than the house again). The comment is that it is generally a better practice to have garage floor lower than living area, and insurance company might said there is a flaw in the house design to try to get away with insurance claim if water soak through concrete floor/wall and getting into the living area. In someway I am thinking I will take that risk as I think it is better to work with the natural landscape. Re: Question about garage and house floor level 4Dec 02, 2012 7:59 am I would always go for the garage floor below house floor level. Don't think that drains will take all the water from your house in a severe storm. Most council stormwater drains have a design capacity for storm events between 2 and 5 year return periods. Any worse conditions is they will be full and won't take any excess. which will then start to pond around the house. Last year we had a storm with a 50 year return period. It flooded the garage to the house floor level but no further. The flood only lasted for 10 minutes so minimal damage to the garages, but it would have been a major problem if it had got into the house The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Question about garage and house floor level 5Dec 02, 2012 1:30 pm bashworth I would always go for the garage floor below house floor level. Don't think that drains will take all the water from your house in a severe storm. Most council stormwater drains have a design capacity for storm events between 2 and 5 year return periods. Any worse conditions is they will be full and won't take any excess. which will then start to pond around the house. Last year we had a storm with a 50 year return period. It flooded the garage to the house floor level but no further. The flood only lasted for 10 minutes so minimal damage to the garages, but it would have been a major problem if it had got into the house Fair enough. That's why I am thinking of making a 30cm concrete wall between the garage and the living areas to protect that event.. if it only last 10 minutes I think that will hold. 10cm is really not much if the water ever comes in. isn't a garage level with the rest of the house a given? pretty sure they 'came around' long time ago. if you have a flat block, the garage is usually level with the rest… 1 17527 interesting situation what happened after builder issued final invoice? did you list as defect or not does the building surveyor have any responsibility? ie. issuing… 13 46966 they can, it's a fairly standard solution when the slab isn't recessed. the falls need to be in the main floor, if it hasn't been done then you need to ask them to redo… 4 6595 |