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attic fan on roof

What’s the Best Temperature for Attic Fans?

At what temperature should I set my attic power vent fans to keep my attic cool? I live in a hot and humid climate, where temperatures are often in the 90s. The roof gets full exposure to the sun throughout the day.

Our Answer

Attic ventilators generally turn on between 90 and 110 degrees Fahrenheit.  That said, attic fans are not the best choice for cooling attics, especially if you have central air conditioning.  The reason is that attic fans depressurize attics and can rob air conditioned air from the main body of the house, greatly decreasing efficiency.  It essentially pulls that cooled air through cracks and crevices in the attic floor, and also through holes that allow for wires and pipes.
A much better cooling option is continuous ridge and soffit venting.  Basically, you cut a slot in the top ridge of the roof and put a vent right over it.  As the wind blows over the roof, it depressurizes the ridge and sucks the moist warm air from the attic.  Everything you want to vent from the attic gets sucked out of that ridge through the depressurization that happens through the normal wind cycle.

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Renovation Tips for a Finished Attic

My attic is partially finished, with another section that is not finished at all. I'm planning to finish both attic sections. What steps do I need to put in place to ensure proper ventilation, insulation, etc. in this situation? I will be doing this myself other than windows, electric, and plumbing.

Our Answer

Finishing your attic is a great project because it is an area of the home most people don't take advantage of! So, it makes a lot of sense to utilize it as a living space. Insulating an attic space like that, however, is difficult. Basically, you want as much insulation as you can get.

However, in a finished attic, you don't have a lot of room to work. At the uppermost level of the home, you most likely want to have 15-20 inches of insulation. This is almost impossible to achieve in a finished attic situation. Typically, you're going to be insulating the underside of the roof rafters - and if it's fiberglass insulation, you have to leave an extra couple of inches for fiberglass insulation.

For this reason, I think your best move is to avoid fiberglass insulation and use spray foam insulation instead. Spray foam insulation is much denser and does not need to be ventilated like fiberglass insulation. It's going to be more expensive for the initial installation, but you will find that it provides many benefits. In addition to insulating, it will also seal the entire attic from drafts. Plus, it has the added benefit of being sound proof. This is why I believe it is the best way to go!

Good luck with your project and be sure to send us pictures when you're done!

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mold in attic

Attic Moisture: Mold in Attic

I have moisture in my attic. I have rusted nails through my sheathing and it looks like mold is starting to form.

I have soffit and continuous ridge ventilation, and the bathroom and kitchen vents are vented to the outside. What can I do?

Our Answer

Moisture in the attic oftentimes can be frustrating.  More so when you have provided what is considered all the right things in ventilation and exhaust installs.

To understand why this is happening you must figure out what the moisture source is.  It has been my experience when issues such as yours has come up that the moisture source is coming from the inside living area of the home and is being drawn into the attic through was is called Stack Effect.

Stack Effect is the result of poor air sealing both in the basement and in the attic combined. Believe it or not, the basement has a lot to do with the performance of the attic vent system.   What happens is as the air in the house is warmed up it rises. Much like a chimney.  When this happens it moves up taking indoor moisture with it.  I am sure you or someone you know has a home that suffers from dry air in winter months?  This is all caused by air moving out of the home. When we think this air is moving out of the walls, and it is, most is going up and out through the roof.  The result is the moisture condenses on the colder areas of the attic. The nails and the area closest to the ceiling which is around the soffit locations.  As the air move up in the middle of the attic it tends to cool down and mix with the air in the attic and is drawn out through the vents.  But when it enters near the soffit it hits the cold roof before it mixes with the air in the attic and condenses.  This is why in most cases we find the attic stained near the soffit areas. But quite often then not we blame the soffit area for pulling in the damp air in that location.

In any case we need to stop the air flow entering into the attic. This will stop the moisture flow and the result will be no moisture, no mold, and no rusted black stains where the nails enter into the attic.

To do this we must first find were the air is entering. This is easy.  If the attic has insulation, pull it up wherever there is a wall below. This can be the outside wall area or where any wall that makes up a room below is located.  Look at the insulation. If its fiberglass you will see black stains in the fibers.  This is dust.  This dust is the result of air movement with the fiberglass acting like a filter. This is a sure fire method of finding exactly were the air is entering.  You will find it wherever wires enter into the attic, plumbing pipes, chimney come up and out. And even around the access hatch or staircase is placed. 

To fix this you need to purchase spray foam insulation.  I use the window and door type as it is a little less foamy then the regular stuff.  The standard foam in can expands way to much and can get a bit messy wen working with it.  In anycase, regardless of what foam you purchase, you need to pull up insulation and foam both sides of the exposed board that is the top plate of the wall below. Any wire openings you need to do the same thing. Plumbing as well.  When you get to the chimney you need to baffle this. Normally there is a fairly large space between the brick and the framing of the ceiling. This is done for fire protection. Purchase thin metal sheets and form and cut them to fit around the opening blocking off as much of the hole as you can.  Then using fire blocking foam.  Seal off the metal to the chimney and framing area.  Once done this would be a great time to add insulation while your up there.  But your not done yet.

Go to the basement and do the same thing. Purchase foam 2" boards and fit them into the mud sill area over the block foundation wall.  Using the high expansion foam (the messy kind) spray around the edges of the framing, place the precut foam boards into this space and foam them tight to the wood.  This will air seal the wall so no air moves up it towards the attic.  Foam all the pipe openings, wire openings and around the chimney in the same manner as you did in the attic.

Once done you not only will prevent this moisture from collecting in the attic on the underside of the roof, you will save a lot of heat and increase your comfort level by stopping drafts that pull the moisture out of the house.

In effect this is the same thing we do as Building Performance contractors  only using large foam machines instead of the little cans.

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Man installing ridge vent

Whole House Attic Fan vs. Ridge Vent

I have a 1300 sq/ft house with 8 foot ceilings that recently had a metal roof put on.  They didn't exactly cut away wood where the ridge vent is even though they installed a ridge vent.  There is a 1.5x1.5 vent at 1 gable end and we have soffet vents.

My question is, how much attic ventillation do you need to run a whole house attic fan with a house  similar to mine.  Also, any web sites you recommend to review products such as this.

Our Answer

It sound's like the house attic fan installation was not done correctly.  A ridge vent installed over solid sheathing is useless.  My first step would be to make the installers one back and cut back the sheathing at the ridge to open up the ridge so the vent will work.  Next step, make sure you have continuous soffit vents.  If those two sets of vents are in place, you DO NOT need an attic fan.  Using one can actually drive cooling costs up.  Read why attic fans can waste money for more info. 

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Attic Ventilation: Impact on Air Conditioning Costs

Does opening the door to the attic have a affect on the AC efficiency in the house? In the hot weather, I keep my 2 garage doors open and the back rear door to get air flow to keep the garage cool in the Arkansas summers. I also have a screen door to the attic which has steps to walk up (unfinished and insulated) and is located in the garage. I use this to ventilate what little air that will get up the steps to the attic which has several attic spinners. In listening to your show I hear you tell people not to create a void in the attic and that house AC will be drawn to it? I am in an all electric house and actually my electric bill has been very reasonable. I use a setback thermostat and cool the house mainly early evening till midnight.

Our Answer

Using an attic fan can have a negative impact on AC costs as the fan will depressurize the attic drawing cooler, conditioned air into that space and out to the environment.  It sound's like in your case the attic may be over the garage?  If that is the case there is no issue.  If the attic is indeed inside living space, then leaving it open will not help your cooling costs.  

This said, most of the concerns stem from the use of attic fans and not passive venting which is what you've described. More here about attic fans and air conditioning.

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How to Insulate an Attic That Has No Soffit?

What is the best way to insulate the floor of an attic if the house does not have soffit vents - or any soffits at all?  There is a ridge vent and two gable vents for ventilation.  Do I need to install special soffit-less vents, or can I insulate right into the corners of the attic, right up to the roofing boards?    I live in New England and am concerned with ice dams.

Our Answer

There's a type of vent called an edge vent, specifically designed for this purpose.  Edge vents basically extend the roof edge by a few inches so you can pick up space for soffit insulation.  A ridge vent is good, but is only half the equation. 
Unfortunately for your situation, edge vents are best installed as part of a larger roofing project.  The roof basically starts at the edge of an edge vent, so it's difficult to add them after the fact. 

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Pulldown Attic Stairs – What Are My Options?

My attic stairs are old and rickety, but I don't know what type to replace them with.  Do you recommend any particular brands or materials, such as wood versus steel?  Also, I've noticed complaints in online product reviews about the width of their attic stairs being smaller than advertised.  I have roof trusses set at 2 feet on center, so it sounds like I might have to shim the new stairs to get a good fit.  Do you agree?

Our Answer

As you've discovered, there's a wide variety of attic stairs out there.  I faced your exact dilemma when I needed to replace a shaky set of attic stairs in my own home last year.  The starcase I ultimately chose was the Rainbow Attic Stair.  This is a steel product unlike any other I'd ever seen, with a prefab stairwell and an accordion-like stair that unfolds from it.  I find it to be very heavy and very sturdy, and I utilize my attic more as a reult.  Even more, it's much more efficient than traditional attic stairs. 
One tip if you go with Rainbow: You're going to need a couple of strong friends to help lift it into place!  Rainbow Attic Stairs are heavy.  They're also much more expensive than the tradititional attic staircases you find in home centers.  In my opinion, the investment's worth it if you use your attic stairs with any regularity, or if traditional stairs leave you feeling unsafe. 
As for your roof trusses, they shouldn't be a problem because attic stairs are designed to fit within the two foot uncenter space.  For example, a 22.5'' x 36'' stair is designed to fit exactly in that opening.

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Do I Need to Pull Up My Attic Floor to Insulate?

I want to add insulation beneath my attic floor, but I'd have to pull the attic floor up to do it.  How will this effect my second floor ceiling? I am worried that the ceiling beneath it is protected by the attic floor.

Our Answer

Certainly your attic floor protects people from stepping through the ceiling beneath it, since that ceiling is not designed to hold weight much heavier than the weight of insulation.  But you probably don't need to remove your attic floor to insulate the space.  You could simply lay insulation above the attic floor - unfaced fiberglass batts, specifically, laid over the floor in the areas you wish to insulate.  If you use your attic for storage, consider consolidating those stored items and keeping them in one area of the floor that you leave exposed.  

Now, if you presently have no insulation whatsoever between the attic floor and the second floor ceiling, take that floor up and insulate it - and restrict the workzone to responsible adults who know where they can and can't place weight.  But if you simply need more insulation in your attic, the easiest bet is to put it over the attic floor.

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Saggy Attic Door Lets in Cold Air

Tom and Leslie, hopefully you can help me.  I have a dissappearing attic stairway that sags, so there is an air gap.  The aluminum folding stairs are mounted on a 1/4" piece of plywood and it's almost like the plywood is warped and won't lay flat.

I'm looking for some suggestions on how the fix this, or a recommendation of who to call for assistance.

Thanks in advance,


Our Answer

Customary dropdown attic stairs are not designed for energy efficiency, and concerns like yours are extremely common.  As those springs stretch, ceilings also settle.  As a result, you get lots of air leakage - not to mention a noticeably uneven ceiling plane. 
One solution is to ignore the sagging factor and install what known as an attic stair insulator.  It's essentially an insulated cover that sits on top of the attic stair area.  You have to remove it every time go up into attic, but the attic stair insulator helps energy efficiency by blocking that attic air from seeping into your living space, and vice versa.  

Another option is a type of stair that's distinctly different, called a Rainbow Attic Stair.  Rainbow Attic Stairs have steel frames that bolt to the door opening and are impossible to twist.  The stairs come down telescope style - in other words, they don't unfold. The door that closes underneath it - the hatch - seals incredibly well.  I went with this option when I improved the efficiency of my own attic last year.  Standard dropdown attic stairs go for about $300, whereas the Rainbow Attic Stair cost close to $1000 after insulation.  However, it's the last attic stair I'll ever need, and I saw an immediate difference in my monthly energy bill.
If you go with either of these options, let us know how it works.  Good luck!  

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Can I Add More Cellulose Insulation to My Attic?

I have cellulose insulation that is R19 in the attic from 1985. Can I just add more of it without removing the old stuff? I live at 5,000 feet and have three seasons: Cold & some snow, temperate spring & fall, and hot summers (up to 105 degrees Fahrenheit). I am not fond of fiberglass for many reasons, and that is what most companies suggest I use.

Our Answer

You certainly can add more cellulose, but only if the existing cellulose if in good condition - that is, it's still fluffy and isn't sagging. 
If this is the case, you could add more cellulose OR add unfaced fiberglass batts.  Lay the batts on top of and perpendicular to the floor joists in the attic, edge to edge.  The additional blanket will improve the attic's insulation.  You can do that with up to 10-inch batts which when combined with the existing 6 inches of cellulose would give you R49.

I don't know how strong your opposition is to fiberglass, but if you're willing, give it some thought.  It's good stuff, the few the drawbacks being that you lose storage space (you can't put stuff on top of it) and you must make sure you have attic on attic insulation, because fiberglass gets moist in the winter, and ventilation is needed to dry it out. 

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Easy Repair For Loose Drywall Tape?

There is a seam in our upstairs ceiling where the drywall tape is peeling up.  I know I can repair this, but I am worried about the cause.  It's just in one little section, maybe two feet long, right above this ceiling is the attic.  Should I be looking into attic humidity levels?  Is there a way to test that?  Our attic has a vent on the side but no roof mounted vent.  I just want to make sure I'm not covering up a potential problem by repairing the dry wall tape.

Our Answer

No need to read so much into a loose tape seam.  It rarely indicates a serious problem. Ceilings in particular expand and contract along seams as well as intersections with walls, causing tape to loosen.  
To fix this, you need to cut out the old tape with a utility knife, because this loose tape will never reseal.  Next, apply fiberglass drywall tape, which is mesh and perforated.  You can trowel and spackel across and through that.  Finally, apply a drywall compound on top of the fiberglass tape to restore the seam.  Once that's complete, you can prime and repaint.  

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Attic Insulation in Old House

I have an old farmhouse, vinyl sided, with no attic insulation. There is no ridge cap, soffit or side vents. Can I lay down fiberglass insulation on the floor of attic and/or between rafters? What are my options?

Thanks Harley in Swansea

Our Answer

Good or bad an old farmhouse is drafty as I'm sure you know.  The best thing is to combine the proper amount of attic ventilation with insulation, so the insulation stays dry.  The first step is to add 15-20 inches of insulation in the attic.  Lay it across the floor joists.  This will make a huge difference in your comfort.
To add some additional ventilation, add gable vents if they don't exist.  Gable vents are not as efficient as ridge and soffit, but gable vents plus the drafty house should provide enough ventilation for the insulation to work properly.

When you need to reroof, be sure to add a ridge and soffit vent system for ulimiate vent efficiency.

Another insulation option is to consider spray foam - products like Icycne are perfect for old farm houses.  It can be directly applied to the underside of roof sheathing.  In this case the attic is not required to be vented and the spray foam insulation will insulate and seal drafts at same time.

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Attic Ventilation: How Much Do You Need?

We just finished installing 23ea 16X8 eave vents in our home. Last year we had a new metal roof installed on our home. Roofing contractor sold with the metal roof a ridge cap. When I look at the roof plan from the insurance company they list the ridge as 65lf. Two weeks ago I added blown-in insulation in the attic, it took me a week to get ready for the insulation job. When in the attic I finally had noticed that the roofer had never cut an opening for the Ridge cap. I contacted the roofer and he sent out a crew and they said they cut a 2" opening 20' long, I have not went back up in the attic yet to verify. My question is will 20' be enough. Attic space is roughly 2250 sq feet. The vents we installed have 3ea 3" holes cut out for ventilation. Insulation I added is about 24" deep in the attic. I have vaulted the ceilings in two rooms in our ranch style house. Roofplan shows roof area is 3910sf. Last winter we had ice dams at every valley on house and snow would be melted off our roof in just a few days. I hope I have given you enough information.

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How to Create Task Lighting

I'm just moving my jewelry-making design work to our bonus room over the garage. I need ideas for lighting for various work areas. The room has one double window facing west. Existing lighting consists of 4 recessed lights and a ceiling light/fan. There is an un-insulated storage space behind one wall. Concern regarding heat & cold for storing supplies such as polymer clay, acrylic paints, etc. Organizational ideas are also welcome. I hope this challenges you and that answers are highly effective. Thanks so much!

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How to Properly Ventilate an Attic

I have an older house built in 1965. It has three gable vents and no soffit vents. Would you recommend that I put in soffit vents? If so, how far apart from each other should they be? Or are the three gable vents efficient enough?

Our Answer

Homes built in the 1960s are notorious for having inadequate ventilation. In my 20 years as a professional home inspector, I frequently found evidence of delamination and mold in the plywood sheeting of those roofs.

You're smart to add additional ventilation. Here's the best way to do it. The most effective attic ventilation is continuous ridge and soffit ventilation. I would replace all solid soffits on the house with ventilated soffit material.

But that's only half the improvement. The other part is to add a continuous ridge vent along the peak of the roof. Together, the ridge and soffit vents will properly ventilate your attic 24/7, 365. As a last step, I would seal off all the gable vents. If you have continuous ridge and soffit vents in place, gable vents will only cause turbulence and negatively impact the efficiency of your ridge and soffit system, which will carry out heat in the summer and moisture in the winter.