Converting Cellar to Livable Space
hi all – this has been covering before a little while ago, so thought I’d re-ask. We are in a row house in Carroll Gardens and are looking to lower our cellar floor by as much as safely possible. Any questions we should surely ask our would-be contractors? What price is justifiable? And I don’t know if this violates any forum rules, but any suggestions are surely welcome for contractors who are dependable and won’t start a domino reaction that topples all our neighbors’ homes. Thanks and be well.
brooklynschlepper
in General Discussion 4 years and 2 months ago
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restorationcontractor | 4 years and 2 months ago
Steve, you absolutely do not need to pay me! I am not usually in Queens unless I am headed upstate, but you’re not that far from me anyway. Give me a call when you are not too busy and we’ll figure something out.
As far as the girder you could install it between the joists you would have to shore both sides cut out a “slot” down the middle and install an I beam or LVL with joist hangers attached to your existing joists. Problem with this is usually there are mechanicals in the way. Here is an example;
https://www.aconcordcarpenter.com/replacing-a-load-bearing-beam-with-a-flush-beam.html
Depending on the weight this is going to carry you could also potentially install a smaller girder like a 4″ wide flange beam, the drawback it the smaller the height the more columns you are going to need. Like the W4x13 at the bottom of the chart.
https://www.engineeringtoolbox.com/american-wide-flange-steel-beams-d_1319.html
andriywww1990 | 4 years and 2 months ago
@ bill resto, thank you. I need to pay you for your time to come by here and talk to me about this – but more than that i want to put some footings in and maybe lift the sag in my floor. I need to know placement of footings and columns or if i should just put a girder down the middle. But if i cannot drop the basement floor a foot, i am not running a girder.
If you are ever over this way, pls let me know.
stevecym | 4 years and 2 months ago
So, when a neighbor added a room on a house on LI when i was a teen, we were paid to dig the footing. We had to go to 48″. In that kind of house, unattached, water and such will run into the soil, so the depth is below the frost line. But what about in a poured concrete celler that is already beyond 48″, how deep below the floor surface will they go? As little as possible? What about if a basement is mostly below grade in the front but opens to the back at grade (built into a hill), will the foundation go deeper in the back? I am trying to figure if i can safely dig 16″ out without disturbing the footing and then pour a 4″ slab.. or would i want a deeper slab near the footing, to sit against it.
hkapstein | 4 years and 2 months ago
Technically it may be possible to dig a little, but it’s unlikely an engineer will find that you can dig very much in brownstone without underpinning or benchwall/bench footing. The builders didn’t generally make the foundation much deeper than necessary, I’d suggest they often made it less deep than necessary. And a stacked stone foundation is not particularly forgiving. Underpinning can be, done, it may cost 30-50k(with a competitive bid) for this project, and possibly involve some negotiation with the neighbors. A bench footing is a little cheaper but it requires space in the room be used. The bench is built around the perimeter of your basement to resist the lateral load of the soil under the foundation so you can dig around it. Unlikely underpinning, the deeper the cellar is dug below the foundation, the wider the bench fotting must be, so it will reduce our cellar square footage. So it might be a good option if you need 6 inches of height, but less so if you need 3 feet.
Messing up could create millions in liability for you if the neighboring buildings are damage d, or if someone is injured so it’s important to have insured contractors and proper paperwork. I’d make sure the underpinning contractor or sub has third party action over insurance, and that you are a named insured. It may be necessary to trigger the blanket additional insured on the policy, so make sure you know wha that means. I’d look for someone who has at least 5 million.
I’v worked with Kemba Walcott http://kceengr.com/ and Tarek Zeid https://tmzeidengineer.com/ on these projects.
restorationcontractor | 4 years and 2 months ago
We have used Becker engineering on our projects, they are familiar with older structures.
bepc.us/contact-us-2/
Steve, I have a vast amount of experience doing this work, I would be happy to talk it through with you whenever you want, you can absolutely handle it, it’s just alot of labor.
Collapses are caused by idiots who have no idea what they are doing and cut corners once they are in over their heads.
I remember your house, are you talking about excavating in your shop area? I assume you’re not looking for too much additional height? If I remember correctly you have poured concrete foundations?
My shop is in an M-1 zone so we did my own basement, went down 12′ deep, 80′ long to gain square footage. Soil was glacial till with huge granite boulders, very difficult work, but I am very happy with the results. I would be glad to show you if you want.
If you need my number email me and I will get back to you.
stevecym | 4 years and 2 months ago
I am curious. Do you have stone or block or poured concrete. I want to hear what the pros say about these and the reply above hit on it. I was planning to dig my basement out on my own and pour slabs against the footings but not knowing how deep they go and then a near collapse of three buildings ten years back put all notions of this out of my head. I suppose that near collapse was a stone foundation but since that happen, anytime a neighbor thinks this is going on without going through proper channels, they willl drop a dime.
Guest User | 4 years and 2 months ago
We’re an architecture firm that does this sort of work. I second the recommendation that you should have an engineer look at your situation. However, a test pit will be necessary, and may tell you what you need to know. If the foundation walls on both sides go below your basement slab, you can lower your floor without great efforts. If it does not, there are other options, but they will come with complications and/or a loss of floor area. We often use Ivan Design Engineering Associates (iluk@id-engineers. com) for this type of work.
brooklynschlepper | 4 years and 2 months ago
any suggestions for engineers? (again, not sure allowed on this forum, but would love some dependable names). Thanks all!
restorationcontractor | 4 years and 2 months ago
Brooklynschlepper what Steve said you need start with an initial engineering consultation. Assuming it’s feasible you will then have to dig test pits in various locations to determine the existing footing depth.
If you need to underpin you are going to need neighboring property owners permissions and you will need to have their buildings monitored for movement.
The other option is benching, where you are not excavating under the foundation but providing a wall on the inside of your cellar, typically at a 45 degree angle from the existing footing. For example if you want to excavate 2′ down you will need to be 2′ away from the existing foundation wall, plus your bench wall thickness.
Once you have approved engineering plans then you can solicit bids from contractors.
There is no way to comment on pricing without more information.
stevecym | 4 years and 2 months ago
Talk to an engineer first.