Welcome to the DoItYourself Forums!

To post questions, help other DIYers and reduce advertising (like the one on your left), join our DIY community. It's free!

Concrete furniture construction help needed

UstenTX's Avatar

Join Date: May 2017
Posts: 2

05-18-17, 02:22 PM   #1 (permalink)  
Concrete furniture construction help needed

Hey, Im looking to make a hollow concrete cube. or 5 sided box...
Like this Name:  cube.JPG
Views: 109
Size:  28.9 KB

I have some experience with concrete but im outa my league...maybe.
So I built a pressure treated wooden box very solid. and wrapped it in stucco wire mesh and treated it with Sika bonding agent... Name:  IMG_20170517_141401.jpg
Views: 113
Size:  43.9 KB
Name:  IMG_20170517_141651.jpg
Views: 80
Size:  39.1 KB
Then i made a brown coat:
4 parts cement
6 parts sand
1 part admix
1 part water
1 part lime

Trowled it on and kept it wet for a day or so... So now i want to finish coat it and im looking for some help...

I made 4 of them with base layers of varying texture. The plan was to mix a white cement mix and trowel it on and smooth it out or sand it down smooth. I was going to use the bonding agent in between coats and just go for it... I just dont want to waste my time or have it start cracking later... so far its really solid and seems strong... any thoughts?
Name:  IMG_20170517_201935.jpg
Views: 92
Size:  35.9 KB
Name:  IMG_20170509_200826.jpg
Views: 87
Size:  31.4 KB

Sponsored Links
Marq1's Avatar

Join Date: Sep 2016
Posts: 1,472

05-18-17, 05:57 PM   #2 (permalink)  
My only concern is if the wood gets wet from being outside it might swell and crack the coating.

UstenTX's Avatar

Join Date: May 2017
Posts: 2

05-18-17, 06:54 PM   #3 (permalink)  
Its pressure treated... but yeah im worried about that too... I thought of using a foam core but like the stability of the wood... How do houses not swell? Obviously they do... Maybe i should use tar paper like the stucco guys do? so the wood can move under the concrete?

Thanks for the comment

marksr's Avatar
Forum Topic Moderator

Join Date: Mar 2005
Posts: 42,076

05-19-17, 05:43 AM   #4 (permalink)  
The main purpose of the tar paper under the stucco is to keep moisture off of the wood. Concrete can/will hold moisture.

retired painter/contractor avid DIYer

Pilot Dane's Avatar
Group Moderator

Join Date: Mar 2003
Posts: 15,918

05-19-17, 06:02 AM   #5 (permalink)  
Is the plywood pressure treated? It looks untreated.

Still, wood is wood and will tend to expand and contract with changes in humidity. That applies to both treated and untreated wood. All the treatment does is help prevent rotting. When building stuff like that I sheet it in Hardie Backer or cement board. It also makes the project easier & faster as chicken wire is not needed.

Yes wood framed houses swell and shrink. My office building is from about 1920. Every summer the bathroom door scrapes near the bottom and every winter a huge gap opens up.

tightcoat's Avatar

Join Date: Jul 2003
Posts: 1,644

05-19-17, 11:24 AM   #6 (permalink)  
it would have been better to wrap them in tar paper before the wire but you have them built so to finish them:
If you want a smooth finish use the same mix you browned them with only if you want them white use white Portalnd.
BUT make the mix a bit richer and add more lime,
1 cement : 1/3 lime : 2 1/2 sand.
If you want smoother screen the sand through a screen the size of window screen. Measure the volume of sand after you screen it.
Apply this in two passes. Grind the first pass well into the brown coat. Then add another coat right away. You want about 1/4" max. As the finish sets you mist it with a little water to lubricate the trowel and trowel it smooth as smooth as you like. You may have to wait a while between trowelings. You will know if you are doing it too soon.
Oh you might also need to moisten your boxes before you apply the finish. You can tell if it is too dry your finish will not spread well
I think it won't hurt to use the admixture since you used it in the brown.

If you are where there is a stucco supply house the easier way is to buy smooth exterior stucco finish. Mix and apply according to the directions, if any. on the bag

DCAbrahams's Avatar

Join Date: Jun 2017
Posts: 1

06-25-17, 11:26 PM   #7 (permalink)  
Hello!!!!! above box looks great, however why not purchase new one?

Search this Thread