Max driveway grade 4

[Surcharged]

An architect friend of mine is grading a driveway for a house with a slope of 25% down from the street to the parking pad. I told him that this was too steep, especially during ice storms. However I am from a flat part of the world and may not be thinking about this correctly. I appreciate any input that you may have.

 

[civilperson]

He will do fine until it is for sale.

 

[tsgrue]

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Have y'all checked the local development codes (building, site, subdivision, and zoning)? Also check out your State insurance regulations regarding such (and how those relate to ADA requirements).

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tsgrue: site engineering, stormwater
management, landscape design, ecosystem
rehabilitation, mathematical simulation

http://hhwq.blogspot.com

 

[cvg]

10% - 15% is a more typical maximum slope limit. If he persists in designing it this way, he needs to provide a gradual transition to the street so he will not scrape his bumper every time he backs out

 

[PELS]

Way too steep! He needs a longer path of travel to flatten the grade out. Kinda like a switchback, but I don't know how much room he has to work with.

Delivery trucks would have major problems.

I've seen buildings that were that far below the street designed with a garage at street level and stairs down thru the bulding. That's just one option.

The 25% is asking for problems.

 

[TerryScan]

Aside from the issues that arise when road surface conditions are poor, there will likely be a problem with sight distance when exiting the drive.

 

[WILDWINGS27]

I would never go above 8%....25% is going to look terrible. Can you lower the foundation?

 

[Erich870]

12% max, any more and you'll never be able to control your assent/dissent in freezing rain or snow, not to mention the vehicle approach angle issues.

 

[concretemasonry]

Park you car with warm tires on it after any snow, and it will end up in the street. - Also, at 25%, be careful not to get any soap under tires when you wash the car.

 

[msucog]

i hope he has a helicopter to move in/out...doubt a moving truck will make that transition. i agree with those above...bad idea. i've got a steep drivway in a neighborhood at a culdesac...probably 15%+ and it's way too steep. it happens to work ok i suppose since we're at the end of the road. it's nightmare trying to back down for fear of running over kids or backing in to someone. i can't imagine it being on a normal road. and a moving truck won't make it up...

 

[civilman72]

Classic Architect "stuff"...

Biggest issue to have the Architect think about is emergency vehicle access, which should be a much bigger concern than moving van access. In my area (big-time snow), emergency vehicles generally do not attempt to access any homes via a driveway grade over 10%. Depending on the length of the driveway and the weather conditions, this could significantly increase the response time of a paramedic or fire department, and this increase in time could be the difference between life or death.

Tell the Architect this and he may/should be more willing to spend the time/money necessary to lessen this grade.

If you have any involvement in this design, I would highly recommend that you limit your liability, or just have him find another engineer.

 

[Kealoha]

I've seen steeper. The owners had to have the lot and it was close to the street. My guess is that they had to build there. They had a v-8 4x4s for autos and they had to exercise extreme care in all maintenance and moving related activities. It can work, but resale will be awsome. If a code was written to protect the future owners of the property I believe they would be dis-served by a municipality that allowed this grade

 

[Hoagie]

Your fire marshall/authority will have something to say (laughing) about the 25%, no doubt. Check with them. Usually, they like it less than 12%--which I believe is national fire code. Again, check...and be sure to check out everything you read on this blog. FYI: I've successfully argued steeper grade by agreeing to specify concrete surfacing (in lieu of AC) with deep scoring.

 

[dec4trax]

The grade is to steep. If you agree to this constrruction plan, you will regret it for as long as you live there. As for resale, the house will sell when you drop the price enough that the trade-off for such an inconvienience is worth it to the next buyer. Be prepared for a lower than average market value on resale if you want it to move.

I lived in a house with a 18% driveway and I agree with all the concerns and comments issued above. Lots of shoveling and de-icing in the winter, friends would not visit, and delivery trucks had to stop in the street.

Avoid such a plan under all circumstances.

 

[msquared48]

Ask him how many mufflers he is willing to buy.

Mike McCann
McCann Engineering