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John D
John D, BS Degree in Engineering.
Category: General
Satisfied Customers: 9666
Experience:  Math, science and 25 years experience in computer programming
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Correcting Cement stairs

Resolved Question:

I recently had cement steps and deck poured at my cottage. The deck and stairs were also stamped to look like slate and colored.
When they removed the forms, the steps were 13 inches long with a 7 inch rise,I had requested the stairs to be15 inches long with a 7 inch rise. Now the contractor has broken off the front 3 or 4 inches of the steps, on almost a 45 degree angle, and is going to repour the steps and also repour and additional 2 inches on the deck and stairs.
Is this proper procedure for such an expensive mistake?
Have you ever heard of such a procedure and is this the way to fix this problem?
Should he be using some sort of stainless steel anchors in the front of the steps and should there be some sort of adhesive used on the existing cement before the new cement is poured ?

Thank-you VERY much !!
Submitted: 10 years ago.
Category: General
Customer: replied 10 years ago.
Relist: I still need help.
Expert:  John D replied 10 years ago.

There are two basic problems with the suggested procedure, structural and appearance.

The tread nosing (the outer edge of the step) is the most vulnerable part of the stair. This small over-hanging edge is where most of traffic load is concentrated, and it is where most of the impact occurs. Joining concrete in such weak-point area is not recommended, even if special measures when joining concrete subjected to stresses, such as placement of steel dowels (to resist tensional stresses which the concrete by itself cannot resist), special bonding agents, and most importantly, the areas to be joined should be large enough to enable the new and old concrete to hold together. Because of the small size of the added part and the concentrated stresses such measures are not practical and cannot be properly applied to the step nosing.

The second aspect is an aesthetic one. The joint between the old concrete and the new cannot be fully concealed. It will always have a 'line' and the colors will not fully match.

Making a mistake in the size of step by 2 inches is in my opinion a serious one, and you should not accept anything short of replacement the entire stair.

Hope this helps and good luck.

Customer: replied 10 years ago.
Reply to John D.'s Post: I think there is a little confusion....The contractor has broken off almost HALF of each of the stairs already and is going to pour over the entire stair not just the remaining half. He will be pouring 2 inches over the entire stair with the cement flowing into the new stair forms.The cement will also be flowing to form 2 inches over the deck that was poured .Nothing is being joined by butting fresh with new, the whole area is being poured over.There will be 2 inches of fresh concrete being poured over everthing at this point to avoid different cement colour concerns. I understand the stress points on the stair nosing but is it O.K. to chip away Half of the stair,leaving half of the stair intact and just repour over everything again with another 2 inches of cement?
Expert:  John D replied 10 years ago.

I see. So

he intends to pour concrete using vertical forms covering the entire 7" height of each step, at a distance of 2" away from where the old edge used to be. If that is the case, then it should be ok, provided:

  • The thickness of the new concrete at any point should not be less than 2", preferably 3"

  • All surfaces of old concrete in contact with the new should be chiseled to produce a relatively rough surface.

  • Place wire mesh along the entire surface.

  • Apply good concrete bonding agent to the old concrete surface before pouring.

  • Use extra strength cement mix.

  • Cement mix should not be just a cement mortar (i.e. cement and sand only). It should have fine to medium gravel as well.

  • If you want to go an extra step, you can ask him to place steel dowels at say 18" apart - (drilling in the old concrete and placing special steel anchors which would extend into the fresh concrete and be tied to wire mesh).

  • Ask for a two year warranty.

If he follows the above procedure, you should be ok. Otherwise, like I said before, this is not just an oversight or a simple mistake in dimensions. It is indeed a serious one and he should fix it to your complete satisfaction.

Please let me know if you need further assistance.

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