Getting ready for a concrete padio...PLZ HELP

Reply

  #1  
Old 08-20-10, 06:57 AM
Member
Thread Starter
Join Date: Sep 2008
Location: Buffalo NY
Posts: 80
Received 0 Votes on 0 Posts
Exclamation Getting ready for a concrete padio...PLZ HELP

Hi guys,
Well Im getting ready for my backyard padio and I had a few questions. Im pretty handy (just finished a lot of work in the house)and would like to try to do it myself but everyones telling me the jobs too big. The padio I plan on having is 44' wide by 17' deep...Pretty much the width of the house. I had some quotes and the job was priced at about $3500...sound about right?

Heres the questions:
1) One of the guys(cheaper estimate) said since the house was built in 1978 I probably wouldnt need stone and he could pour the slab right on the dirt after leveling it. This didnt sound right. I thought you should have about 4" of rock under your slab.

2)Some guys at work said they got their padios pinned to the foundation wall and its never moved. Im sure I can do that, drill holes, pound in rebar etc. Is this neccessary?

3)Any tips/DIYs/websites that would help me pour the padio myself...before I hire someone to do the job?

Thanks guys
 
Sponsored Links
  #2  
Old 08-20-10, 08:44 AM
Member
Join Date: Oct 2008
Location: New England
Posts: 10,432
Received 26 Votes on 24 Posts
Not a pro on this topic, but have done some and seen a lot. You are certainly in cold country so frost is an issue. When you look right next to the foundation, the heat loss usually prevents any substantial amount of frost. However, depending upon the soil type and the drainage, you could experience as much as 6" of lift in the soils 6' to 10' away from the foundation. This can require some slope to the patio to prevent water and ice from pooling up next to the house. To prevent the lifting, you would need to change the soils and the drainage. Of course I don't know what is there, but you would need surface drainage and a substantial gravel base that can drain below the surface away from the slab.

IMO, 2' or more gravel base, with a gravel layer of the same depth sloping away from the area. Slab on soil will most likely lift with the frost. Adding 4" of gravel would do little to change that.

Like I said, not a pro, but have seen the results of doing it wrong.

Bud
 
  #3  
Old 08-20-10, 09:00 AM
Member
Join Date: Aug 2009
Location: USA
Posts: 4,947
Received 0 Votes on 0 Posts
Originally Posted by Bud9051 View Post

IMO, 2' or more gravel base, with a gravel layer of the same depth sloping away from the area.
Bud
I think you mean 2", right?

I'm not an expert either. I wouldn't want to pin it to the foundation because if it heaves, it will either crack your slab or mess with your foundation. I woudl stay away from that. The best thing to do is to encourage good drainage like Bud has suggested. A good silicone caulk between the slab and the foundation may also be a good idea to prevent water from getting in between and freezing.

Don't forget to put in any expansion/control joints in your patio that you may need.
 
  #4  
Old 08-20-10, 09:35 AM
Member
Join Date: Oct 2008
Location: New England
Posts: 10,432
Received 26 Votes on 24 Posts
Hi Drooplug, no, I was saying 2 feet of gravel base and depending upon the soil, that may not be enough. Where my house is located I have 90% clay and have to create below grade drainage paths for everything. It's a lot easier to add the gravel now than later.

Bud
 
  #5  
Old 08-20-10, 10:59 AM
Member
Join Date: Aug 2009
Location: USA
Posts: 4,947
Received 0 Votes on 0 Posts
Oh. So the 2' of gravel under the entire patio is more like a dry well?

I think I'm about 99% clay with a high water table. I'm working on replacing one of my retaining walls and I consider myself lucky that we haven't had rain in a long time. I'm saving on frustration when digging and on the tipping fees at the dump.
 
  #6  
Old 08-20-10, 11:41 AM
Join Date: Mar 2005
Location: USA
Posts: 6,130
Received 0 Votes on 0 Posts
rugsr -

You need a compacted base under the patio that could range from 4" to 24", depending on the soil you have. Some clays can be pretty bad even if they look good. Rock is not very good because a clean rock cannot be compacted.

You will have to remove your lawn and some natural soil, so it just a question of how thick and few more loads is not going to cause a job to be canceled.

For that size, you will need a couple of experienced finishers. You will also have to form or saw cut some joints for crack control. In your climate, air entrained concrete (minimal extra cost) should be used for durability. Around here, some concrete suppliers will not supply any concrete for a slab on grade use, but you can find some small suppliers that might.

Pinning a patio to a foundation can lead to big problems in colder climates. If it gets cold and the edge heaves, the drainage will be back toward the house because they are pinned together and can possibly affect the basement or foundation.

Regarding the price, I had a 12'x20' exposed aggregate patio with wire mesh poured 5 years ago for $2000. Costs have gone up since then and they vary from city to city and upon access to the area poured.

Dick
 
  #7  
Old 08-20-10, 12:01 PM
Member
Thread Starter
Join Date: Sep 2008
Location: Buffalo NY
Posts: 80
Received 0 Votes on 0 Posts
Thanks guys,
Yea actually Amherst (where I am) is pretty loaded with clay and used to be swap. People around here have basement issues, cracks etc. My basement is dry thank God.
Next to the house a yr ago it used to be really wet. Around the house settled and the slop was towards the house. A gutter was also broken so after fixing that and adding some dirt, along with adding Perf. Pipe (tieing into my drainage system) this year its been pretty dry around the house, even with the storms.

24" of stone is alot! Whats a good type of stone to use. I have also toosed around the idea of building the pad about a step higher the grade and using 8x8x16 blocks around the perimeter. What if I do this and fill it all in with stone. Will that be ok or no since under the stone is the same soil?
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description: