GalileoG
Structural
- Feb 17, 2007
- 467
I am evaluating an existing roof deck to receive new roofing for a building which was constructed sometime in the 1950s. Original drawings show that a 4-1/2" thick 'aerocrete' roof deck spanning up to 7' between beams. No other information is shown regarding concrete strength or density. There is no information to suggest that the 'aerocrete' deck is reinforced, which is surprising given that the building is located in a zone of moderate snow load. Condition of roof deck is unknown (soffit is also hidden).
Can anyone shed some light on this deck system? Was it normal back then for a roof deck to span 7' without reinforcing?
Architects will want to put new roofing which is heavier than original roofing and I want to draw a line in the sand early.
The way I see it, there are three ways to approach this:
1) Assuming there is no visible deterioration once the original roofing is removed and deck is exposed, new roofing can be placed provided that it does not weigh more than the original roofing.
2) Allow heavier roofing provided that the capacity of the deck can be verified and there is no visible deterioration once the original roofing is removed and deck is exposed. How can one even verify the capacity of this deck? What testing would be performed other than concrete strength/density? Would you allow new load on an unreinforced 'aerocrete' deck? Personally, I am hesitant.
3) Replace the 'aerocrete' deck with a steel deck from the onset. This allows architects to place a heavier roofing system and eliminates risk of changing design to steel deck mid way during construction should deterioration be discovered once the roofing is removed. This is likely not feasible but may end up being the end result if the aerocrete is found to be deteriorated.
Let me know what you think and which angle you would push, or if there are other options.
Can anyone shed some light on this deck system? Was it normal back then for a roof deck to span 7' without reinforcing?
Architects will want to put new roofing which is heavier than original roofing and I want to draw a line in the sand early.
The way I see it, there are three ways to approach this:
1) Assuming there is no visible deterioration once the original roofing is removed and deck is exposed, new roofing can be placed provided that it does not weigh more than the original roofing.
2) Allow heavier roofing provided that the capacity of the deck can be verified and there is no visible deterioration once the original roofing is removed and deck is exposed. How can one even verify the capacity of this deck? What testing would be performed other than concrete strength/density? Would you allow new load on an unreinforced 'aerocrete' deck? Personally, I am hesitant.
3) Replace the 'aerocrete' deck with a steel deck from the onset. This allows architects to place a heavier roofing system and eliminates risk of changing design to steel deck mid way during construction should deterioration be discovered once the roofing is removed. This is likely not feasible but may end up being the end result if the aerocrete is found to be deteriorated.
Let me know what you think and which angle you would push, or if there are other options.
