Builder knocked a hole in the drywall above the water heaters

Based on recent recommendations I've seen by weatherization contractors to make sure to control all movement of air from the living space to the attic, it seems like this was a mistake.

The articles I've read say that even before you add insulation, it is critical that you have completely sealed the ceiling of all penetrations that will allow moist air into the attic.

Unfortunately, I've already added another 6 inches of insulation in the attic.


Does anyone know why the builder would do this?

Also, is this something that I should seal off?

 

http://www.airbarrier.org/aboutairbarriers.htm

This organization supports and promotes the restriction of air movement within the structural components (cavities) of the structure. It is good to note that air tight structual components or air barriers if you prefer seek to direct air movement to components of the structure that are least affected by the air movement. In other words, air movement inside, in and out of the structure is essential to not only the structural integrity of the structure but also to the health and well being of the occupants.

The information you provided leads me to make two possible assumptions.

1. The contractor accidentally or inadvertently put the hole in the drywall.

2. The water heater and/or other applicance in this area is a combustion applicance. Which would require 15 cubic feet of air to burn one therm of gas. The hole in the drywall may be a fresh air supply for combustion.

 

Thanks for the reply.

The holes are obviously deliberate as they are identical in two different hot water heater closets.

Both units are gas, so your second point may be the answer.


If that is the case, then it sounds like I need to leave the holes there and treat the closets as 'unconditioned spaces' within the footprint of the 'conditioned space.'

In the pursuit of this, I need to make the closets themselves as airtight as possible in an attempt to make them separate from the living space envelope.


Does that sound right?

 

Im with resercon here . But Id call code there where you are and ask them about it. You dont say where the heaters are. You could grill the door to the room they are in if its small. ID have to think about a hole there in the ceiling that goes up into the attic for air/

ED

 

The hole in the ceiling cannot be the only fresh air supply source. There must be another hole/vent towards the floor area. The rule here is universal, one square inch of net vent area for every 1,000 BTU/hr; one high and one low. The average water is 35,000 BTU/hr. rating, so you would require two vents 7 inches by 5 inches (7 x 5 = 35 square inches). Net vent area excludes the register itself, so the vents are larger than 7 x 5 inches.

You must be made aware of the lower vent because far too often people store things in closets like these and block these vents. Carbon Monoxide is a result of insufficient gas burn due to inadequate amount of fresh air and in conjunction with poor draft. Most hot water heater are natural draft units. The draft hood located on top of the water heater allows air from the closet to go up the flue with the flue gases. This is to maintain the proper draft. The rule here for natural draft applicances is 15 cubic feet of air to burn completely one therm of gas and another 15 cubic feet of fresh air to maintain proper draft. For a total of 30 cubic feet of fresh air for every therm of gas burnt. Blocking the lower vent in these closets with stored items can result in health problems to the occupants to death. I respectfully request you read carefully the aforementioned and everyone else in the family be made aware of the vents. You may store items in this closet, just make sure you do not block the vents. However, I would caution you with combustionable items like paint and paper products.

Yes, I would treat this closet as an unconditioned space and seek to prohibit heat loss/gain to this area from the rest of the house. But first I would determine if the fresh air supply vents operated properly. The easiest way to do this is blow hot air into the lower vent with a hair dryer and go into the attic and put your hand over the duct to feel the heat coming from the hair dryer. If not, then there may be something obstructing the duct or may be either not connected or disconnected.

 

Wow! Thanks for the insightful reply. It would appear that you have a good deal of knowledge of things other than insulating!

Both of these closets also have a vent near the floor that fits the description you indicated.

I will proceed as you suggest.


Should I also plan on filling the closet walls with insulation? They are surrounded on all sides by 'conditioned space.'

 

Yes, I would recommend insulating the walls with the vapor barrier facing the conditioned area. I would also recommend insulating the water heater and both the cold and hot water pipes in the closets. The reason for this is once you insulate the walls and make the doors air tight, the heat radiating from the water heater will lose temperature rapidly. You will notice condensation almost immediately on the cold water pipes. This is because heat condenses on cool surfaces and the cold water pipes will be the coolest surface in the closet. The insulation on the water heater and pipes will allow reduce the amount of heat radiating from the water heater and lower the probability of condensation occurring dramatically.

 

I was thinking I read that if you blow cellulose in through a hole in the top of the wall, and you make sure to over-pack it, you don't need a separate vapor barrier.

Is that true?

If so, it would be nice b/c I wouldn't have to tear out a bunch of drywall.

 

Cellulose retards heat flow by providing several paths for conduction and relies less on trapped air inside it to do the same. Whereas fiberglass uses the trapped air inside the insulation to retard heat flow. This is why the manufacturers of cellulose say their product does not require a vapor barrier. Along with the paint on the walls, I agree with installing cellulose without a vapor barrier.

 

Thanks resercon.

You've been a tremendous help.

 

Holes in Drywall remain illegal for fire code reasons as they compromise the 1 hour fire-rating that sealed drywall provides.

Even if the builder cut holes in the drywall for air intake reasons, it will have been illegal because of fire code issues. You cannot give access for a fire to enter stud or joist cavities where it can then spread to other parts of the home.

You need to have your local code office do an inspection here and make recommendations.

From here, it appears the holes offer some serious and dangerous code violations.

 

Thanks Homebild.

I haven't ever been in touch with a 'codes' office. How should I go about contacting them?