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yummy mummy 11-13-2006 12:00 AM

building a soffit can I use 2 X 2s
I am building a soffit around some heating vent and it happens to be against the concrete block wall.

I would like to know if I can use 2 X 2s for this, and also if I need to install the 2 X 2s against the concrete wall, can I still use the concrete anchors to do that.


AtlanticWBConst. 11-13-2006 06:26 AM

If you attach it directly onto the concrete, then, make sure that the lumber you use, is pressure treated. Any other lumber attached into the pressure treated can be regular KD. Also make sure that the fasteners you use are galvanized or stainless since the new pressure treated lumber: ACQ (Analkaline Copper Quat) or CBA, CB-Bd (Copper Azole) will react with and corrode normal untreated nails (brights) and untreated screws...

FWIW - If we have to build out a soffit in the basement, we normally build our 2x4 walls and then build out our soffits by attaching to the 2x4 walls, not the concrete freeze walls....

Good Luck...

yummy mummy 11-13-2006 08:01 AM

Thanks for the info.

I will be constructing the wall (as I am doing with all my walls) with 2X4.

I will build out with 2X2s.

Thanks so much, (I am almost finished with two walls).
I must say, that I am impressed with myself given that this is pretty new to me. :)

AtlanticWBConst. 11-13-2006 08:37 AM

Just so you knw, if you use 2x2's and install directly onto concrete with tapcons .... they usually end up splitting the wood.

yummy mummy 11-13-2006 09:00 AM

Thanks for the tip about the 2X2s splitting.

I won't do that. I plan to attach them to to the framed wall.

Love ya atlantic. You have been such an amazing help to me. :yes:

KUIPORNG 11-13-2006 12:35 PM

2x2 building soffit is good... I also find the problem though is it is too easy to splitas it is kind of two thin, especially those 2x2 sold in home depot, they are not one piece wood, but many small pieces link together... I therefore, build my soffit this way which you may want to considered, I kind of invent this method myself as I never see anywhere in the book using this method, I used 2 inch metal tracks to attach a track to solid backing, like 2x4 wall frame or ceiling..etc. than insert 2x2 L sticks between them and wrap the corner with metal corner L shape wrap... I don't know if building the whole think with 2x2 alone will be able to substain the structure as 2x2 is really not strong even holding against the main wall frame... the book suggest use OSB boards to put on top of the 2x2s which to me is too much work... and attaching 2x2 to main wall frame would be a challenge where as attaching a 2 inch metal track is a piece of cake...

yummy mummy 11-13-2006 02:16 PM

Thanks for the advice.

I hope I won't have a problem attaching them to the 2X4s that are the main wall frame.

I know what you mean by that they are not all one piece. You can see them attached all the way along.

I hope I won't split them.

yummy mummy 11-13-2006 02:19 PM

My book also shows to use OSB board, but I agree, too much work.

But I am wondering if I have to use it.
Or can I just drywall over the 2X2 framing around the duct work?

KUIPORNG 11-13-2006 02:34 PM

I think the main problem is 2x2 alone is kind of too weak... using drywall as support is not enough... and it is not suppose to be like that... I heard of drywall is part of the support for metal framing, but not for wood framing... although this is kind of academic knowledge rather than practical experience, but I could kind of six sense it is kind of correct....

may be later on someone else with more experience will give some input... but I wouldn't myself build a soffit solely by 2x2 against on 2x4 wall frame... I have kind of not too trust it's strength... but I kind of never tried it either so could not tell you for sure...

AtlanticWBConst. 11-13-2006 07:58 PM


The reason why a narrow piece of wood splits is because of the large 'diameter' of the 'fastener' that you put...into or through it ... forces the wood grain to separate in the direction of the natural grain.

FWIW - If we have a small non-structural soffit to install with narrow pieces of wood, instead of using screws or framing nails, we use a brad nailer or finish gun with a small diameter nail (16, 15 guage nails or 18 guage brad nails). This will not split the wood, but holds it in place to support the weight of the drywall...

Also, as you mentioned, narrow strips of plywood. Don't use OSB.
3/4" CDX plywood will work better. If you screw into these, they will not split. Unfortunately these need to be cut with a table saw (you may not own one).


You can go to some place like Home D. and have them cut the plywood sheets or the 2' x 2' scraps (They do sell these) .... for you to a width that you need. Strapping width is good (2 1/2")
You can then cut the lengths down to the size you need...

Just a suggestion...

(Also, when you attach the sheet-rock to flimsy soffit framework, it locks it into shape and makes it ridgid....)

yummy mummy 11-13-2006 08:18 PM

This weekend I did purchase some 2X2s at Home D.
But I really like your suggestion of the plywood.

I am going to look into it.


yummy mummy 11-13-2006 08:27 PM

If I decide to use the plywood for soffit framing, would I be able to cut them into any size that I want or do they all have to be 2 1/2 inches?

So I gather that you can install drywall on plywood also?

(Have never thought of that, but what a great idea)

Thanks again

yummy mummy 11-13-2006 08:29 PM

Yes, you are right, I have no table saw.

Just a hand saw that I am using.

(Takes me approx. 5 minutes to cut a 2X4)

(I think I'll have the basement done by the time my 10 year old goes to university.) :laughing:

AtlanticWBConst. 11-14-2006 07:57 AM


Originally Posted by yummy mummy (Post 23598)
If I decide to use the plywood for soffit framing, would I be able to cut them into any size that I want or do they all have to be 2 1/2 inches?

2 1/2 inches was the width of the strips that I suggested, if you want them a different width, then yes you can have them cut into a different size.


Originally Posted by yummy mummy (Post 23598)
So I gather that you can install drywall on plywood also?
(Have never thought of that, but what a great idea)

yes, absolutely you can.

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