Cellulose Insulation

blown in cellulose attic insulationBlown in cellulose is a highly effective, environmentally friendly insulation solution. Made from recycled newspaper and treated with borate for fire retardance, the even distribution of blown in cellulose insulation makes for a high performance insulation that has come into increasing favor among green builders and building energy efficiency experts. It is our preferred insulating material because it is so simple and works so well.

A few reasons we like blown in cellulose insulation:

Environmentally Friendly.

Cellulose is made from recycled newspaper, so it's an earth-friendly insulation solution. You can also rest assured that it's a safe product to have in your house -- no formaldehyde, no harmful chemicals.

Consistent High Performance. 

Because cellulose is blown into cavities as small particles rather than installed in batt form, it's far less likely to come with gaps and air leaks around the edges. This means that you get consistent high performance - for a cozier, more energy efficient home.

Fire Retardant. 

Cellulose is treated with the flame retardant borate, which is highly effective at slowing down the spread of fires. A house that is insulated with blown in cellulose insulation is safer from a fire-hazard standpoint than an uninsulated house. 

Loose Blown Cellulose

This installation method is exactly as what it sounds like.  Bales of cellulose are fed into a blower machine in the back of the installation truck.  The cellulose is fed through a hose to the area of the house to be insulated and blown as a loose blanket to the depth required.

Before we blow the insulation we need to do air sealing including covering any recessed lights.  If insulating an attic we then fit baffles to the perimeter of the attic to ensure we do not interfere with airflow that keeps the underside of the roof deck cool and dry and prevents ice damming which can destroy a roof.

We prepare the house with drop cloths and place cardboard rulers to ensure the correct depth of cellulose.

Loose blown cellulose is an attractive insulating material because it settles into every nook and cranny between your existing insulation and any forgotten spaces in plumbing chases, dropped soffits and the like. It helps the existing insulation to work better as well as adding its own layer of R-value.

Doesn’t it settle? 

It settles a bit and we allow for that.  We blow more than the contracted depth so that you get the final R value specified.

Doesn’t it make a mess? 

Again to be very honest; there will be a bit of dust during installation.  We minimize it as best we can, and we do clean after the installation.

Doesn’t it blow around when it gets windy or if I turn on my whole house fan? 

No, it sits like a nice blanket.  We have tried it with very large whole house fans and have seen no movement.  Full disclosure; at one house the owner reported some cellulose blown around during hurricane Sandy.  We will check it out, but suspect it is a very rare combination of wind speed, location and maybe something to do with the soffits.

Can I put plywood sheets on top, nail them to the floor joists and use the attic for storage? 

No!  If you compress the loose cellulose you lose R-value.  However, as part of our comprehensive approach to giving you an energy efficient and comfortable house we have raised the attic floor above the height of the cellulose in a number of our customers’ houses.  We put up a raised set of floor joists, blow the cellulose and then put sheets of ply (or similar material) on top to provide storage and walkways.

To summarize; the benefits of blown insulation include:

  • Increased energy efficiency and savings on electric bills
  • Ability to resist mildew and mold growth, making for a more healthy environment
  • Moisture-less installation means there is no waiting for the materials to dry enough to enclose them
  • Extremely high R-values of up to R-70 can be achieved without 
exceeding the weight limits of ½” drywall, making it an effective option where other insulation would be too heavy or not provide enough protection
  • Blown insulation only settles one to three percent after initial installation, meaning it retains its R-value much longer than other types and does not require as much upkeep
  • This material is not corrosive
  • Easy to install in both new construction and existing structures
  • Noise insulation as well as thermal protection

Dense Packed Cellulose

We install dense packed cellulose where the insulation is contained inside a structural assembly, most commonly:

  • Exterior walls
  • Walls between the house and garage, porch, sunroom etc.
  • Garage ceilings
  • Floored attics, including kneewall floors
  • Overhangs, bay windows, cantilevered floors

To dense pack we drill holes, insert the cellulose feed hose and then withdraw it slowly to leave a dense fill of cellulose.  There are standards on how dense it must be, but it feels solid to the touch when complete.  This method is known as “drill and fill”.

Because we compress the cellulose, against all the advice we just gave, it loses some of it’s R-value and gives us R 3 per inch versus the R 3.75 per inch for loose blown.  On the plus side however it means that the cavity is completely filled with insulation and the dense pack provides a measure of air flow reduction – not perfect, but good.

What about those holes?

Good question!  For dense packing we need to drill holes, about 1 ½” in diameter, one hole for each joist or stud bay – so roughly 16” apart.  It depends on what we are drilling into:

Exterior walls with vinyl or wood siding (shakes or boards) are easy.  We remove a row of siding half way up each floor level, drill our holes, pack the cellulose, plug the holes and replace the siding.  We take every care in removing and replacing the siding.  With wood we caulk the nail holes, but you may have to do some touch-up repairs and painting.

Exterior walls with stucco, brick, aluminum or asbestos exteriors we do not touch from the outside – they need to be drilled from the inside.  Again we drill about half way up the wall.  We insert the hose downward and fill, then up and fill.  We plug and spackle the hole.  We sand, spackle again if needed and leave it ready for you to repaint.

Garage ceilings and overhangs are treated the same as exterior walls.  Attic floors are the same again.  Usually we just plug the holes because the cosmetics are not so critical.

What if there is insulation in there already?

During the energy audit we try and make sure we know what is in there.  We use an infra-red camera if we can – i.e. if there is enough difference in inside and outside temperature to get a good contracting picture.  We drill holes and use a bore-scope to look and see, and we use our experience and your input and knowledge.

If the cavity is partly filled then the dense packed cellulose compresses the existing insulation and fills the rest of the void.  It is excellent for this purpose.  We often find that owners complain of cold rooms above a garage.  The garage ceiling might be built with 2x8 joists and have 6” fiberglass (we’ve seen them with just 3”).  It means there is an air gap of an inch or more below the floor of the room, allowing air to freely circulate there.  No wonder the room feels cold!  The dense packed approach is ideal for rectifying this situation.

If the cavity is fully filled and the installer cannot get the hose in to fill then we close up and, of course, don’t charge you.

You haven’t mentioned cathedral ceilings.  Why?

Hmm.  We sort of hoped you wouldn’t notice.

Cathedral ceilings are difficult beasts to insulate properly.  We are probably too cautious in our approach.  We absolutely want to do no harm or cause you problems in the longer term.

There is an on-going debate in our industry about insulating cathedral ceilings.  Based on our opinion, and on advice from our installer, we will not dense pack sloped roof assemblies with cellulose.  The reason is that even dense pack cellulose will settle a little and in the sloped assembly this could lead to long-term moisture problems.

Ideally of course they should have been well insulated during construction.  For retro-fit insulation the right way is to either add insulation from the outside, when you are having a roof replaced, or by taking out the interior ceiling and either using spray foam, or installing baffles, fiberglass and insulating board before replacing the interior drywall.